Musannaf Ibn Abi Shayba 3:1005

Hafs narrated to us, from Hajjaj, who said: I asked 'Ata' about a man who prayed on a cloudy day, and then it turned out that he had prayed facing other than the Qibla. He said: "It suffices him." He said: And someone who asked Ibrahim and al-Sha'bi narrated to me, and they both said: "It suffices him."