'The Prophet was asked about a man who forgets prayer or sleeps and misses it. He said: 'he performs it when he remembers it.'"  

سُئِلَ النَّبِيُّ ﷺ عَنِ الرَّجُلِ يَغْفُلُ عَنِ الصَّلاَةِ أَوْ يَرْقُدُ عَنْهَا قَالَ يُصَلِّيهَا إِذَا ذَكَرَهَا  

"The Messenger of Allah said: 'Whoever forgets a prayer, let him perform it when he remembers it.'"  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ نَسِيَ صَلاَةً فَلْيُصَلِّهَا إِذَا ذَكَرَهَا  

When the Messenger of Allah was coming back from the battle of Khaibar, night came and he felt sleepy, so he made camp and said to Bilal: "Keep watch for us tonight." Bilal prayed as much as Allah decreed for him, and the Messenger of Allah and his Companions went to sleep. When dawn was approaching, Bilal went to his mount, facing towards the east, watching for the dawn. Then Bilal's eyes grew heavy while he was leaning on his mount (and he slept). Neither Bilal nor any of his Companions woke until they felt the heat of the sun. The Messenger of Allah was the first one to wake up. The Messenger of Allah was startled and said: "O Bilal!" Bilal said: "The same thing happened to me as happened to you. May my father and mother be ransomed for you, O Messenger of Allah!" He said: "Bring your mounts forward a little." So they brought their mounts forward a little (away from that place). Then the Messenger of Allah performed ablution and told Bilal to call the Iqamah for prayer, and he led them in the prayer. When the Prophet finished praying, he said: "Whoever forgets a Salah, let him pray it when he remembers, for Allah says: And perform the prayer for My remembrance." [Ta-Ha: 14] He (one of the narrators) said: "Ibn Shihab used to recite this Verse as meaning, 'when you remember'."  

أَنَّ رَسُولَ اللَّهِ ﷺ حِينَ قَفَلَ مِنْ غَزْوَةِ خَيْبَرَ فَسَارَ لَيْلَةً حَتَّى إِذَا أَدْرَكَهُ الْكَرَى عَرَّسَ وَقَالَ لِبِلاَلٍ اكْلأْ لَنَا اللَّيْلَ فَصَلَّى بِلاَلٌ مَا قُدِّرَ لَهُ وَنَامَ رَسُولُ اللَّهِ ﷺ وَأَصْحَابُهُ فَلَمَّا تَقَارَبَ الْفَجْرُ اسْتَنَدَ بِلاَلٌ إِلَى رَاحِلَتِهِ مُوَاجِهَ الْفَجْرِ فَغَلَبَتْ بِلاَلاً عَيْنَاهُ وَهُوَ مُسْتَنِدٌ إِلَى رَاحِلَتِهِ فَلَمْ يَسْتَيْقِظْ بِلاَلٌ وَلاَ أَحَدٌ مِنْ أَصْحَابِهِ حَتَّى ضَرَبَتْهُمُ الشَّمْسُ فَكَانَ رَسُولُ اللَّهِ ﷺ أَوَّلَهُمُ اسْتِيقَاظًا فَفَزِعَ رَسُولُ اللَّهِ ﷺ فَقَالَ أَىْ بِلاَلُ فَقَالَ بِلاَلٌ أَخَذَ بِنَفْسِي الَّذِي أَخَذَ بِنَفْسِكَ بِأَبِي أَنْتَ وَأُمِّي يَا رَسُولَ اللَّهِ قَالَ اقْتَادُوا فَاقْتَادُوا رَوَاحِلَهُمْ شَيْئًا ثُمَّ تَوَضَّأَ رَسُولُ اللَّهِ ﷺ وَأَمَرَ بِلاَلاً فَأَقَامَ الصَّلاَةَ فَصَلَّى بِهِمُ الصُّبْحَ فَلَمَّا قَضَى النَّبِيُّ ﷺ الصَّلاَةَ قَالَ مَنْ نَسِيَ صَلاَةً فَلْيُصَلِّهَا إِذَا ذَكَرَهَا فَإِنَّ اللَّهَ ﷻ قَالَ {وَأَقِمِ الصَّلاَةَ لِذِكْرِي} قَالَ وَكَانَ ابْنُ شِهَابٍ يَقْرَؤُهَا {لِلذِّكْرَى}  

"They mentioned negligence because of sleeping too much, and he said: 'They slept until the sun had risen. The Messenger of Allah said: "There is no negligence when oneis sleeping, rather there is negligence when one is awake. If anyone of you forgets to pray, or sleeps and misses a prayer, then let him pray when he remembers, and during its time if it is a day after. (Sahih)'Abdullah bin Rabah said: "Imran bin Husain heard me when I was narrating this Hadith and said: 'O young man, look at how you are narrating the Hadith. I was present at the time of this Hadith with the Messenger of Allah.' And he did not deny anything of the Hadith."  

رَسُولُ اللَّهِ ﷺ لَيْسَ فِي النَّوْمِ تَفْرِيطٌ إِنَّمَا التَّفْرِيطُ فِي الْيَقَظَةِ فَإِذَا نَسِيَ أَحَدُكُمْ صَلاَةً أَوْ نَامَ عَنْهَا فَلْيُصَلِّهَا إِذَا ذَكَرَهَا وَلِوَقْتِهَا مِنَ الْغَدِ قَالَ عَبْدُ اللَّهِ بْنُ رَبَاحٍ فَسَمِعَنِي عِمْرَانُ بْنُ الْحُصَيْنِ وَأَنَا أُحَدِّثُ بِالْحَدِيثِ فَقَالَ يَا فَتًى انْظُرْ كَيْفَ تُحَدِّثُ فَإِنِّي شَاهِدٌ لِلْحَدِيثِ مَعَ رَسُولِ اللَّهِ ﷺ قَالَ فَمَا أَنْكَرَ مِنْ حَدِيثِهِ شَيْئًا