Musannaf Ibn Abi Shayba 21:48

Yazid ibn Harun narrated to us, he said: Abd al-Rahman ibn Abi Bakr informed us, from Musa ibn Uqbah, from Nafi, from Ibn Umar, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever among you has the door of supplication opened for him, the doors of response have been opened for him."