Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.141B.

He would recite Qafor al-Qamar completely, and sometimes al-A’la and al-Ghashiyyah. The rightly guided caliphs did the same. Once Abu Bakr read al-Baqarah in the morning prayer until the sun was about to rise. They said, “O successor of the Messenger of Allah, the sun is about to rise.” He said, “Had it risen, you would not have found us negligent.” ‘Umar would recite Yusuf, an-Nahl, Hud, al-Isra’ and similar surahs. If reciting long surahs was abrogated, it would have been known to the khalifahs or to those who may have criticized them. Muslim records from Jabir ibn Sumrah that the Messenger of Allah, upon whom be peace, recited Qaf in the morning prayer, and that his subsequent prayers during that day would be shorter. Umm al-Fazhl heard Ibn ‘Abbas recite al-Mursilat and she told him, “O my son, that recital reminded me of that surah. It was the last one that I heard the Prophet, upon whom be peace, recite, and he read it in the sunset prayer.” That is one of the latest actions that we have from him.

Given the above, we may now interpret the Prophet’s hadith, “O you who lead the people in prayer, be easy on them,” and Anas’ statement, “The Prophet, upon whom be peace, conducted the prayer very lightly, though it was complete.” ‘Easiness’ or ‘lightness’ is a relative term. We must return to how the Prophet behaved to understand and follow his example correctly. It is not to be determined by the whims and desires of those who are present for prayer. The Prophet, upon whom be peace, did not order the people to differ from his practice, even though he knew that behind him were the aged, weak and people with needs to tend to. He performed his prayer in the same manner that he asked others to pray–‘light’ or ‘easy’. If his prayers were somewhat long, they were still easy compared to how long he could have made them. The guidance that he came with and practiced is the one that decides our affairs and disputes for us. This is supported by the hadith recorded by an-Nasa’i and others in which Ibn ‘Umar reported that the Prophet, upon whom be peace, ordered those who lead prayers to be ‘easy’ by reciting as-Saffat. Therefore, a surah the length of as-Saffat is part of what the Prophet, upon whom be peace, meant when he said that the imams should be easy on the people.