Abu Hurairah reported:
When the Messenger of Allah (ﷺ) returned from the Battle of Khaibar, he travelled during the night. When we felt sleep, he halted for rest. Addressing Bilal he said: Keep vigilance at night for us. But Bilal who was leaning against the saddle of his mount was dominated by sleep. Neither the Prophet (ﷺ) nor Bilal nor any of his Companions could get up till the sunshine struck them. The Messenger of Allah (ﷺ) got up first of all. The Messenger of Allah (ﷺ) was embarrassed and said: O Bilal ! He replied: He who detained your soul, detained my soul, Messenger of Allah, my parents be sacrificed for you. Then they drove their mounts to a little distance. The Prophet (ﷺ) perfumed ablution and commanded Bilal who made announcement for the prayer. He (the Prophet) led them in the Fajr prayer. When he finished prayer, he said: If anyone forget saying prayer, he should observe it when he recalls it, for Allah has said (in the Qur’an): “Establish prayer for my remembrance”. Yunus said: Ibn Shihab used to recite this verse in a similar way (i.e. instead of reciting the word li-dhikri – for the sake of My remembrance – he would recite li-dhikra – when you remember). Ahmad (one of the narrator) said: ‘Anbasah (a reporter) reported on the authority of Yunus the word li-dhikri (for the sake of my remembrance). Ahmad said: The word nu’as (occurring in this tradition) means “drowsiness”.
Sunan Abi Dawud 435
Abu Qatadah reported:
“The Prophet (ﷺ) was on a journey. The Prophet (ﷺ) took a turn and I also took a turn with him. He said: ‘Look!’ I said: ‘This is a rider; these are two riders; and these are three’ until we became seven. He then said: Guard for us our prayer, i.e. the Fajr prayer. But sleep dominated them and none could awaken them except the heat of the sun. They stood up and drove away a little. Then they got down (from their mounts) and performed ablution. Bilal called for prayer and they offered two rak’ahs of (Sunnah) of Fajr and then offered the Fajr prayer and mounted (their mounts). Some of them said to others: We showed negligence in prayer. The Prophet (ﷺ) said: There is no negligence in sleep. The negligence is in wakefulness. If any of you forget saying prayer, he should offer it when he remembers it and next day (he should say it) at its proper time.
Sunan Abi Dawud 437
Khalid b. Sumair said:
Abd Allah b. Rabah al-Ansari, whom the Ansar called faqih (juries), came to us from Medina, and reported us on the authority of Abu Qatadah al-Ansari, the horseman of the Messenger of Allah (ﷺ) saying: The Messenger of Allah (ﷺ) sent a military expedition consisting of the chief Companions. He then narrated the same story, saying Nothing awakened us except the rising sun. We stoop up in bewilderment, for our prayer. The Prophet (ﷺ) said: Wait a little, wait a little. When the sun rose high, the Messenger of Allah (ﷺ) said: Those who sued to observer the two rak’ahs of Fajr prayer (sunnah prayer before obligatory prayer) should observe them. Then those who used to observe and those who would not observe stood up and said prayer. Then the Messenger of Allah (ﷺ) commanded to call for prayer; the call for prayer was made accordingly. The Messenger of Allah (ﷺ) stood and led us in prayer. When he turned away (from the prayer) he said: We thank Allah for the fact that we were not engaged in any wordily affairs which detained us from our prayer. Instead our souls were in the hands of Allah. He released them whenever He wished. If any one of you gets morning prayer tomorrow at its proper time, he should offer a similar prayer as an atonement.
Sunan Abi Dawud 438
In-book : Book 2, Hadith 48
Anas b. Malik reported the Prophet (ﷺ) as saying:
If any one forgets a prayer or oversleeps, he should observe it when he remembers it ; there is no expiation for it except that.
Sunan Abi Dawud 442
In-book : Book 2, Hadith 52