Tirmidhi Chapter 42 Hadith 296

Awf bin Malik Radhiyallahu anhu says: "I spent a night with Rasulullah Sallallahu Alayhi Wasallam. Rasulullah Sallallahu Alayhi Wasallam used the miswaak (cleaned the teeth), then performed the wudhu, then stood up in salaah. I stood with him (joined him). He began reciting the Surah Baqarah. Whenever he came across an aayah of mercy, he paused and beseeched Allah of His Mercy. In the same manner when he came across an aayah of adhaab (punishment), he paused and beseeched Allah for His forgiveness from adhaab. He then performed ruku', and remained in the ruku for as long as he had spent in the standing posture. He recited in the ruku':

Subhaana dhil jabaruti wal-malakuti wal-kibri-yaa-i wal-'a-za-mati.
Translation: Glory be to the Lord of the Might, the Dominion, the Majesty, and the Magnificence.

Thereafter he performed the sajdah, which was as long as the ruku and recited the same du'aa in the sajdah. He then recited the Surah Aali Imraan (in the second rakah), thereafter one surah (in each rakah) and did the same".

Commentary
How lengthy these rak'ahs must have been, is evident from the saying (of the above narration). The Surah Baqarah covers about two and half Juz, and then sayyidina Rasulullah Sallallahu Alayhi wasallam recited with care, every word was recited clearly and distinctly. A pause was with made at every aayah where mercy and punishment are mentioned du'aa was made. Thereafter a long ruku', the same length as that of the standing was performed and likewise was the sajdah. This is one rakah. In this manner it will be difficult to complete four rak'ahs in the whole night. But due to the intense desire and zeal, especially for such a noble personality, whose coolness of the eye was in salaah, such a deed was not difficult. Apparently the last few ahaadith have no relation with the subject on the fasting of Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam. In (some) editions of the Shamaa-il these are included not only in the chapter on salaatud duha, saum etc., but in every chapter on the devotions of Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam. There is no perplexity in this, but in those editions where these different chapters exist, a minute point is derived, that generally those who have a strong zeal for fasting, it is observed that, they begin to exert themselves so much that they tend to become lax in the rights of others. For this reason, Imaam Tirmidhi has in the beginning mentioned the ahaadith on moderation, and in the end has indicated that when in zeal one sometimes exceeds one's normal practice, there is no harm. It must not be of such a nature that an indifference and weariness for 'Ibaadah (devotions) is created as a result of this.