Rashi, on Ps 100:1

“A psalm for David himself. Mercy and judgment I will sing to thee, O Lord: I will sing,”

“I shall sing of kindness and judgment when You bestow kindness upon me, I will praise you [with the blessing:] “Blessed be He Who is good and does good,” and when You perform judgment upon me, I will sing, “Blessed be the true Judge.” In either case, to You, O Lord, I shall sing.”

Imported from an open dataset — not yet checked against the printed edition.