Genesis 9:21-23

21When he drank some of its wine, he became drunk and lay uncovered inside his tent. 22Ham, the father of Canaan, saw his father naked and told his two brothers outside.

23But Shem and Japheth took a garment and laid it across their shoulders; then they walked in backward and covered their father’s naked body. Their faces were turned the other way so that they would not see their father naked.