when Nathan, &c. See 2Sa_11:2; 2Sa_12:1. David's utterance when he lay all night upon the earth as a penitent (2Sa_12:16). Compare his utterance when he "sat before the LORD "as a worshipper (2Sa_7:18-29), and when he "stood upon his feet" as a servant (1Ch_28:2-10).
Have mercy upon me = Be gracious or favourable unto me.
God. Hebrew. Elohim.App-4.
lovingkindness: or, grace.
blot out = erase, as a debt from a book (Exo_32:32, Exo_32:33. Num_5:23. Num_69:28), or wipe out so as to remove (2Ki_21:13. Isa_44:22).