John Gill Commentary Exodus 32:32

"Yet now, if thou wilt forgive their sin-; and if not, blot me, I pray thee, out of thy book which thou hast written." — Exodus 32:32 (ASV)

Yet now, if you will forgive their sin
Of your free grace, good will, and pleasure; it will redound to your glory, men will praise your name on account of it; these people will have great reason to be thankful, and will lie under great obligations to you, to fear, serve, and glorify you; and in particular it will be regarded by me as the highest favour that can be asked or granted:

and if not, blot me, I pray you, out of the book which you have
written ;
not the book of the law, as Jarchi, written with the finger of God, the name of Moses was not written there; nor the book of the just, as the Targum of Jonathan, the list and catalogue of good men, that belonged to the visible church, called in after time "the writing of the house of Israel", (Ezekiel 13:9) but rather the book of life, either of this temporal life, and then it means no more than that he wished to die, even immediately by the hand of God, which seems to be countenanced by (Numbers 11:15) or else of eternal life, and is no other than the book of life of the Lamb, or God's predestination or choice of men in Christ to everlasting life, which is particular, personal, sure, and certain;

and Moses asks for this, not as a thing either desirable or possible, but to express his great affection for this people, and his great concern for the glory of God; and rather than either should suffer, he chose, if it was possible, to be deprived of that eternal happiness he hoped for, and should enjoy.