"Speak to Aaron and to his sons, saying, 'Thus you shall bless the sons of Israel. You shall say to them:
The LORD bless you, and keep you;
The LORD make His face shine on you, And be gracious to you;
The LORD lift up His countenance on you, And give you peace.'
So they shall invoke My name on the sons of Israel, and I then will bless them." " (Numbers 6:23-27) The literal commandment is that the Aaronic priests should bless the sons of Israel using what is traditionally called "The Aaronic Blessing". How frequently this should be done is not specified in this passage.
"A widow, or a divorced woman, or one who is profaned by harlotry, these he may not take; but rather he is to marry a virgin of his own people, so that he will not profane his offspring among his people; for I am the LORD who sanctifies him." (Leviticus 21:14) The high priest (verse 10) may not take a widow for a wife.
"'A widow, or a divorced woman, or one who is profaned by harlotry, these he may not take; but rather he is to marry a virgin of his own people, so that he will not profane his offspring among his people; for I am the LORD who sanctifies him.'"" (Leviticus 21:15) The literal commandment is that the high priest (verse 10) should not profane his offspring [literally: seed] among his people. Since that would occur through sexual relations with someone G-d has forbidden to him this prohibition is understood that he cannot have sexual relations (even outside of marriage) with a widow.
"They shall not take a woman who is profaned by harlotry, nor shall they take a woman divorced from her husband; for he is holy to his God." (Leviticus 21:7) The priests, the sons of Aaron (verse 1) may not take a woman who has been "profaned by harlotry". The Hebrew phrase translated as "profaned by harlotry" uses a word (tzanah) that implies willful and harlotrous behavior.
"The Levitical priests, the whole tribe of Levi, shall have no portion or inheritance with Israel; they shall eat the LORD'S offerings by fire and His portion." (Deuteronomy 18:1) This commandment is literally that the members of the tribe of Levi have no portion or inheritance in the Land of Israel.