Genesis 9:21-24

One day he drank some wine he had made, and he became drunk and lay naked inside his tent. Ham, the father of Canaan, saw that his father was naked and went outside and told his brothers. Then Shem and Japheth took a robe, held it over their shoulders, and backed into the tent to cover their father. As they did this, they looked the other way so they would not see him naked. When Noah woke up from his stupor, he learned what Ham, his youngest son, had done.