Sahih Ibn Khuzaymah

By this, the Prophet ﷺ meant some prayers, not all. The Prophet ﷺ meant four prayers other than the Maghrib prayer. Similarly, when the Prophet ﷺ said, "Then an addition was made in the prayer during residence," by this the Prophet ﷺ meant the three prayers other than Fajr and Maghrib. And the explanation of the evidence for the statement of Sayyiduna Ibn Abbas (may Allah be pleased with them both) that Allah Almighty made four rak‘ahs obligatory upon you through the tongue of your Prophet ﷺ during residence, by this the Prophet ﷺ meant the prayers other than Maghrib and Fajr. Likewise, when he said that in travel there are two rak‘ahs, he meant the prayers other than Maghrib. This is of the same kind as when we say in our books that these words are general but their meaning is specific.

Lady Aisha (may Allah be pleased with her) narrates that (in the beginning of Islam) the prayers for travel and residence were made obligatory as two rak‘ahs each. Then, when the Messenger of Allah (peace be upon him) settled in Madinah Munawwarah, two rak‘ahs were added to the prayer in residence, and the Fajr prayer was left as it was due to its lengthy recitation, and the Maghrib prayer was also left as it was because it is the witr (odd-numbered prayer) of the day. “Imam Abu Bakr (may Allah have mercy on him) says that this hadith is gharib (rare). To my knowledge, no narrator except Mahbub bin Hasan has narrated it in a musnad form. The students of Dawud, while narrating this report, have said « عن الشعبي عن عائشه » (that is, they did not mention Masruq, the teacher of Shu‘bi), whereas Mahbub bin Hasan has mentioned Masruq by name and narrated the chain as connected.