Musannaf Ibn Abi Shayba 7:344

Abu Dawud al-Tayalisi narrated to us, from Harun ibn Ibrahim, from Ibn Sirin, from Abdullah ibn Jubayr, that Zayd saw Abu Musa looking sorrowful. He said to him, "What is the matter with you?" He mentioned that he had taken an oath (of abstention) regarding his wife. So he ordered him to offer an expiation, and he did so.