Sahih Bukhari Volume 4, Book 54, Hadith Number 447.

Narated By ‘Aisha : I stuffed for the Prophet a pillow decorated with pictures (of animals) which looked like a Namruqa (i.e. a small cushion). He came and stood among the people with excitement apparent on his face. I said, “O Allah’s Apostle! What is wrong?” He said, “What is this pillow?” I said, “I have prepared this pillow for you, so that you may recline on it.” He said, “Don’t you know that angels do not enter a house wherein there are pictures; and whoever makes a picture will be punished on the Day of Resurrection and will be asked to give life to (what he has created)?”