Acts 10:4

And when he looked on him Literally, "having fastened his eyes on him." The angel is called (Acts 10:30) "a man in bright clothing." Such a sight would rivet the centurion's gaze at the first, and then the heavenly nature of the visitor made itself evident, and he was afraid.

What is it, Lord? His language expresses his readiness to perform what shall be commanded, and his question implies, "What wilt thou have me to do?"

Thy prayers and thine alms are come[have gone] up The idea is that of the prayers, like incense, when offered ascending up to God. Cp. Revelation 8:3-4, also Acts 10:8, "vials full of odours which are the prayers of saints." Cf. Psalms 141:2.

for a memorial before God They have been such as to be remembered before God, and now He is about to answer them. The portion of the meal offering which the priest was commanded to burn upon the altar to be an offering of a sweet savour unto the Lord (Leviticus 2:2) was called a "memorial," and the allusion is to the offerings of this kind. Cp. the words of the angel (Tob 12:12), "I did bring the remembranceof your prayers before the Holy One," where the Greek word for "remembrance" is that which is here rendered "memorial."