Sunan Abi Dawud Book 4, Hadith 13
The Messenger of Allah (ﷺ) combined the noon and the afternoon prayers, and combined the sunset and night prayers without any danger or journey. Malik said: I think it so happened during rain.
Abu Dawud said: Hammad b. Salamah narrated it like manner from Abu al-Zubair, it has also been narrated by Qurrah b. Khalid from Abu al-Zubair. He said: It is so happened in a journey that we made to Tabuk.
The Messenger of Allah (ﷺ) never combined the sunset and night prayers while on a journey except once.
Abu Dawud said: This has been narrated by Ayyub from Nafi' from Ibn 'Umar as a statement of Ibn 'Umar. Ibn 'Umar was never seen combining these two prayers except on the night he was informed about the death of Safiyyah. The tradition narrated by Makhul from Nafi' indicates that he (Nafi') saw Ibn 'Umar doing so once or twice.
The Messenger of Allah (ﷺ) combined the noon and afternoon prayers, and the sunset and night prayers at Medina without any danger and rain. He was asked: What did he intend by it ? He replied: He intended that his community might not fall into hardship.