“Either make the tree good and its fruit good, or make the tree bad and its fruit bad, for the tree is known by its fruit. You brood of vipers! How can you speak good, when you are evil? For out of the abundance of the heart the mouth speaks. The good person out of his good treasure brings forth good, and the evil person out of his evil treasure brings forth evil. I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned.” Then some of the scribes and Pharisees answered him, saying, “Teacher, we wish to see a sign from you.” But he answered them, “An evil and adulterous generation seeks for a sign, but no sign will be given to it except the sign of the prophet Jonah. For just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth. The men of Nineveh will rise up at the judgment with this generation and condemn it, for they repented at the preaching of Jonah, and behold, something greater than Jonah is here. The queen of the South will rise up at the judgment with this generation and condemn it, for she came from the ends of the earth to hear the wisdom of Solomon, and behold, something greater than Solomon is here. “When the unclean spirit has gone out of a person, it passes through waterless places seeking rest, but finds none. Then it says, ‘I will return to my house from which I came.’ And when it comes, it finds the house empty, swept, and put in order. Then it goes and brings with it seven other spirits more evil than itself, and they enter and dwell there, and the last state of that person is worse than the first. So also will it be with this evil generation.” While he was still speaking to the people, behold, his mother and his brothers stood outside, asking to speak to him. But he replied to the man who told him, “Who is my mother, and who are my brothers?” And stretching out his hand toward his disciples, he said, “Here are my mother and my brother! For whoever does the will of my Father in heaven is my brother and sister and mother.”
the tree is known by its fruit - "Then He made His appeal to them; 'Either make the tree good, and its fruit good, or make the tree corrupt and its fruit corrupt.' Say that you know the tree is corrupt because its fruit is corrupt; or date to say that the tree is good, because its fruit is good. There is in these words the touch of a great pity, of a great desire to help these men. He appealed to them not to attribute good fruit to a corrupt tree. That is what they were doing. They said that the good result, of a man freed from demon possession, was wrought by Satan. He appealed to them to be consistent; to believe on Him for the very works' sake. Then finally He uttered the most awe-inspiring words of all; 'Ye offspring of vipers, how can ye, being evil, speak good things?' The severity of that consists in His evident pity for them. It seems as if even the hopeful spirit of Christ was almost hopeless about these men. He said, How can ye speak a true thing? How can ye say the tree is good because its fruit is good? How can you tell the truth? You are the offspring of vipers; you are morally degenerate; you have lost your moral discrimination." (Morgan)
careless = useless
“Teacher, we wish to see a sign from you.” - "They were not really prepared to receive a sign. If they had been, the casting out of the demons was in itself sufficient to have proved His cooperation with the Spirit of God, as He had declared. Thus when a sufficient sign had been given they had refused it by attempting to account for it in the most terrible way. Yet these men, already hardened against convincing signs, asked for one; and the asking was satirical, the asking of men who were not prepared to accept as sufficient any sign He could give, because of their personal hatred of Him. That is exactly what He meant when He declared in words of the sternest, 'Ye generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.' Their use of the word 'Teacher' was in itself an insult, as they refused to accept Him or His teaching." (Morgan)
adulterous generation - "The nation was unfaithful in its vows to the Lord." (Ryrie)
"Generation is certainly to be understood in the sense of race. The unclean spirit is idolatry. It had left the nation, and even now the nation is swept from that evil spirit unoccupied, and boast of reform. It will not be so forever. The unclean spirit will return and bring seven others with him and take possession of that house again, and the last condition, the end, becomes worse than the beginning. The return of the unclean spirit with its seven companions will take place during the great tribulation." (Gaebelein)
"As compared with the other nations of the world, Israel was like a house from which the demon of idolatry had gone out with all his attendants—really the 'Beel-Zibbul' whom they dreaded. And then the house had been swept of all the foulness and uncleanness of idolatry, and garnished with all manner of Pharisaic adornments. Yet all this while the house was left empty; God was not there; the Stronger One, Who alone could have resisted the Strong One, held not rule in it. And so the demon returned to it again, to find the house whence he had come out, swept and garnished indeed—but also empty and defenseless. The follow of Israel lay in this, that they thought of only one demon—him of idolatry—Beel-Zibbul, with all his foulness. That was all very repulsive, and they had carefully removed it. But they knew that demons were only manifestations of demoniac power, and that there was a Kingdom of evil. So this house, swept of the foulness of heathenism and adorned with all the self-righteousness of Pharisaism, but empty of God, would only become a more suitable and more secure habitation of Satan; because, from its cleanness and beauty, his presence and rule there as an evil spirit would not be suspected. So, to continue the illustrative language of Christ, he came back 'with seven other spirits more wicked than himself'—pride, self-righteousness, unbelief, and the like, the number seven being general—and thus the last state—Israel without the foulness of gross idolatry and garnished with all the adornments of Pharisaic devotion to the study and practice of the Law—was really worse than had been the first with all its open repulsiveness." (Edersheim)
sign of the prophet Jonah - "The sign is the warning of judgment to come (cf. Jonah 1:2; 3:4). Here the sign is related to the death and resurrection of the Son of Man." (Ryrie)
"While refusing a sign He promised a sign; and thus in the presence of their malicious hostility foretold the new opportunity which would be created for them by the carrying out to completeness of His divine work in the world. His purpose was that of saving and redeeming. Therefore He refused the sign they asked, which would have had no effect; and promised them the only sign that could by any means arrest and constrain them, that namely of His own Resurrection from the dead after their malice had encompassed that death. The giving of that sign would afford them a new and final opportunity ... That sign would in all essentials be similar to one with which they were perfectly familiar. They knew how Jonah had been a sign to Nineveh in its sin by virtue of the fact that he had appeared in the city a preacher of Jehovah, after he had been cast out to death. that is the only possible solution of the words of the King here, for in that is the only parallel between Jonah and Jesus. In every other way they stand in contrast." (Morgan)
three days and three nights - "This phrase does not necessarily required that 72 hours elapse between Christ's death and resurrection, for the Jews reckoned part of a day to be a whole day. Thus this prophecy can be properly fulfilled if the crucifixion occurred on Friday. However, the statement does not require a historical Jonah who was actually swallowed by a great fish." (Ryrie)
something greater - "The Greek word is neuter here and in verse 42, and refers to the kingdom of God." (Ryrie)
queen of the South - "Just as the pagan Queen of Sheba acknowledged the superiority of Solomon's wisdom, so the Pharisees should recognize that the kingdom of God was at hand." (Ryrie)
"Less enlightened people had obeyed less enlightening preaching and teaching; and in that fact the patent condemnation of those to whom He spoke, and who were to receive His final sign was declared." (Morgan)
unclean spirit - "A demon. Self-reformation, without spiritual conversion, can lead to serious ramifications. Notice that some demons are more wicked than others, and they can repossess a person from whom they have been cast out." (Ryrie)
whoever does the will of my Father in heaven is my brother and sister and mother - "This means that the spiritual relation between Christ and believers is closer than the closest of blood ties. Obedience to God takes precedence over responsibilities to family." (Ryrie)
"This is not to say that He lost His affection for His brethren, or failed in love to His mother. In the last and awful hours of His intensest suffering, He still thought of her, and with tender solicitude entrusted her to the care of John. His brethren, moreover, according to the flesh, we find eventually numbered among His disciples. But in this hour, when unable to understand Him, they sought from the motive of a true affection to hinder Him in His work, He resolutely refused to yield to their desire, and by His words revealed the fact that He counted earthly relationships as nothing compared to those spiritual relationships which were born of a common loyalty to the will of God." (Morgan).
"The nation Israel claimed a relationship to Messiah when He should come because of a common relationship to Abraham. But Christ rejected blood ties as constituting a true spiritual relationship. The only ones whom He would accept as being spiritually related to Him were those who were related to Him by faith. In that multitude there were those who claimed a relationship to Abraham as a basis for entrance into the kingdom. Christ said the kingdom must be entered by faith in His person, not by the accident of physical birth." (Pentecost)