Straitly charged - See the reason for this, Matthew 8:4 (note). This verse is wanting in two copies of the Itala.

And he straitly charged him;.... Either with the sin which had been the cause of this leprosy, and to take care that he sinned that sin no more, lest a worse evil should befall him; for sin was usually the cause of leprosy, as the cases of Miriam, Gehazi, and Uzziah show. It is said to come upon men for seven things. The seven abominations mentioned in Proverbs 6:16, are said, by the Jewish writers (t), to be the reasons of persons being stricken with leprosy: "a proud look"; as appears from the instance of the daughters of Zion, Isaiah 3:16, the crowns of whose heads were smitten with a scab, and who were attended with a stink, boldness, and burning. "A lying tongue"; as in the case of Miriam, who, with Aaron, spoke against Moses; upon which the cloud departed from the tabernacle, and Miriam became leprous, white as snow, Numbers 12:1. "And hands that shed innocent blood"; which is proved from Joab, on whose head the blood of Abner and Amasa returned; and on account of which a leper was not to fail from his house; see 1-Kings 2:31, compared with 2-Samuel 3:29. "An heart that deviseth wicked imaginations"; which was fulfilled in Uzziah, who sought to bring the high priesthood into contempt, and therefore was smitten with leprosy, which arose in his forehead, while he had the censer in his hands, and was contending with the priests; and he continued a leper to his death, 2-Chronicles 26:18. "Feet that be swift in running to mischief"; which was true of Gehazi, who ran after Naaman the Syrian, and took a gift of him which he should not; for which, the leprosy, Naaman was cured of, seized him, and cleaved unto him, 2-Kings 5:20. "A false witness that speaketh lies"; of this no instance is given. "And him that soweth discord among brethren"; as Pharaoh between Abraham and Sarah; wherefore the Lord plagued Pharaoh, &c. Genesis 12:17, which the Jews understand of the plague of leprosy. These seven things are, in another place (u), said to be an evil tongue, shedding of blood, a vain oath, uncleanness, a proud spirit, theft, and envy. Elsewhere it is said (w), that for eleven things leprosy cometh; for cursing God, for uncleanness, for murder, for saying of a neighbour a thing that there is nothing in it, for pride, for entering into a border which is not a man's own, for a lying tongue, for theft, for a false oath, for profaning the name of God, for idolatry: and R. Isaac says, for an evil eye; and the Rabbins also say, it comes upon him who despises the words of the law: the first is proved from Goliath, 1-Samuel 17:26; the second from the daughters of Jerusalem, Isaiah 3:16; the third from Cain, Genesis 4:15 and from Joab, 2-Samuel 3:29; the fourth from Moses, Exodus 4:5; the fifth from Naaman, 2-Kings 5:1; the sixth from Uzziah, 2-Chronicles 26:16; the seventh from Miriam, Numbers 12:10; the eighth and ninth from Zac 5:4, compared with Leviticus 14:45; the tenth from Gehazi, 2-Kings 5:20; the eleventh from the children of Israel when they made the calf, Exodus 32:25, compared with Numbers 5:2. But whether this man's sin was either of these, or what it was, is not certain: however, he was, by this cure, laid under an obligation, for the future, to avoid it, and all other sins: or rather the charge was to tell no man of his cure, before he came to the priest: nor to him, or any other, how he came by it, and by whom he was healed;
and forthwith sent him away; to the priest, in all haste; and it looks as if the man was unwilling to have gone from him, but chose rather to have continued with his kind benefactor: for the word signifies, he cast him out; he drove him from him; he obliged him to go without delay.
(t) Vajikra Rabba, sect. 16. fol. 158. 1, 2. (u) T. Bab. Eracin, fol. 16. 1. Vid. Abarbinel. in 2 Kings v. 27. (w) Bemidbar Rabba, sect. 7. fol. 188. 2, 3.