Musannaf Ibn Abi Shayba 21:630

Hussain bin Ali narrated to us, he said: I asked Hisham bin Hassan, "What does he say when he sees the crescent?" He said: He used to say, "O Allah, make it a month of blessing, light, reward, and well-being. O Allah, You are the Divider among Your servants of good within it, so divide for us in it from the best of what You divide for Your righteous servants."