Be merciful, O Lord, to thy people Israel, whom thou hast redeemed,.... Out of Egyptian bondage, and claimed as his own; and therefore it is requested he would be favourable to them, and show them mercy, and not punish them for a sin they were entirely ignorant of, though done by some one among them, whom as yet they could not discover.
The words seem to be the words of the elders continued, who having made a declaration of their innocence, humbly request mercy of God, not only for themselves, but for all the people of Israel; yet, both the Targums of Onkelos and Jonathan take them to be the words of the priests, and so does Jarchi, and the same is affirmed in the Misnah :and lay not innocent blood unto thy people of Israel's charge; impute not the guilt of innocent blood to a people in general, when only a single person, and he unknown, is chargeable with it: or put it not "in the midst" of thy people; let it not be placed to the whole, because it cannot be found out whose it is, though it is certain it is one in the midst of them:and the blood shall be forgiven them; that is, God will not impute it, and place it to their account, or lay it to their charge; but will graciously consider the beheading of the heifer as an expiation of it: it is said in the Misnah ,"if the murderer is found before the heifer is beheaded, it goes forth and feeds among the herd; but if after it is beheaded, it is buried in the same place; and again, if the heifer is beheaded, and after that the murderer is found, he shall be slain;''so the Targums, and Jarchi on the next verse.
Ut supra. (Sotah. c. 9. sect. 5.) Hilchot Rotzeach, c. 9. sect.