Musannaf Ibn Abi Shayba 27:161

Waki’ narrated to us, from Salamah ibn Nabit, from al-Dahhak, who said: Gabriel came to the Prophet, may Allah bless him and grant him peace, and recited to him the end of al-Baqarah. When he had memorized it, he said: "Recite it to me." So the Prophet, may Allah bless him and grant him peace, recited it, and Gabriel began to say: "That is for you: 'Do not punish us if we forget or make a mistake.'"