Variantly: "for your voice is sweet" — at the Red Sea, viz. (Ibid. 15:1) "I shall sing to the L–rd, for He is exalted (over all the) exalted." "and Your face is fair" — (Psalms 8:24) "From the mouths of babes and sucklings You have founded strength … When I see Your heavens, etc."
When Was Israel's Voice Sweetest to God
Mekhilta Tractate Bachodesh 3:28