Jamieson, Fausset and Brown on Genesis 3:8

8. they heard the voice of the Lord God walking in the garden--The divine Being appeared in the same manner as formerly--uttering the well-known tones of kindness, walking in some visible form (not running hastily, as one impelled by the influence of angry feelings). How beautifully expressive are these words of the familiar and condescending manner in which He had hitherto held intercourse with the first pair.

in the cool of the day--literally, "the breeze of the day," the evening.

hid themselves amongst the trees of the garden--Shame, remorse, fear--a sense of guilt--feelings to which they had hitherto been strangers disordered their minds and led them to shun Him whose approach they used to welcome. How foolish to think of eluding His notice (Psa 139:1-12).