Sahih Ibn Khuzaymah

Hazrat Nafi’ narrates that I was with Sayyiduna Abdullah bin Umar (may Allah be pleased with them both), Hafs bin Asim, and Masahq bin Amr, when the sun had set. It was suggested to Sayyiduna Ibn Umar (may Allah be pleased with them both) to perform the prayer, but he kept walking (and continued the journey). He was again requested to pray, so he said that when the Messenger of Allah (peace and blessings be upon him) was in a hurry during travel, he would delay this prayer, and I also intend to pray it late. He says that therefore we kept walking until about midnight or close to it, then he dismounted and performed the prayer.

Imam Abu Bakr (may Allah have mercy on him) says that from this hadith and the hadith of Sayyiduna Anas (may Allah be pleased with him) from Ibn Shihab, it is clear and established that it is permissible to combine the Zuhr and Asr prayers at the time of Asr, and to combine the Maghrib and Isha prayers at the time of Isha after the redness of the sun has disappeared. Not in the manner as some Iraqi jurists have said, that the way to combine Zuhr and Asr is to perform Zuhr at its last time and Asr at its earliest time, and to perform Maghrib at its last time before the disappearance of twilight. And according to them, it is permissible to combine two prayers in this manner during travel and residence, because in their view, it is permissible for a resident person to perform all prayers, if he wishes, at their last time, and if he wishes, at their earliest time.