Mishkat al-Masabih 1298
Abu Dharr said:
We fasted along with God’s Messenger, but he did not make us get up at night for prayer at any time during the month till seven nights remained; then he made us get up for prayer till a third of the night had passed. Next night he did not make us get up, but when the fifth remaining night came he made us get up for prayer till a half of the night had gone, so I said, “Messenger of God, I wish you had led us in supererogatory prayers during the whole of this night." He replied, “When a man prays with an imam till he goes away he is reckoned as having spent a night in prayer." On the fourth remaining night he did not make us get up till two-thirds of the night had passed. On the third remaining night he gathered his family, his wives and the people and prayed with us till we were afraid we would miss the falah (explaining, when asked, that the falah was the meal before daybreak). Then he did not make us get up for prayer during the remainder of the month. 

Abu Dawud, Tirmidhi and Nasa’i transmitted it, and Ibn Majah transmitted something similar, but Tirmidhi did not mention, “then he did not make us get up for prayer during the remainder of the month."
عَنْ أَبِي ذَرٍّ قَالَ: صُمْنَا مَعَ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ رَمَضَانَ فَلَمْ يَقُمْ بِنَا شَيْئًا مِنَ الشَّهْرِ حَتَّى بَقِيَ سَبْعٌ فَقَامَ بِنَا حَتَّى ذَهَبَ ثُلُثُ اللَّيْلِ فَلَمَّا كَانَتِ السَّادِسَةُ لَمْ يَقُمْ بِنَا فَلَمَّا كَانَتِ الْخَامِسَةُ قَامَ بِنَا حَتَّى ذهب شطر اللَّيْل فَقلت: يارسول الله لَو نفلتنا قيام هَذِه اللَّيْلَة. قَالَ فَقَالَ: «إِنَّ الرَّجُلَ إِذَا صَلَّى مَعَ الْإِمَامِ حَتَّى ينْصَرف حسب لَهُ قيام اللَّيْلَة» . قَالَ: فَلَمَّا كَانَت الرَّابِعَة لم يقم فَلَمَّا كَانَتِ الثَّالِثَةُ جَمَعَ أَهْلَهُ وَنِسَاءَهُ وَالنَّاسَ فَقَامَ بِنَا حَتَّى خَشِينَا أَنْ يَفُوتَنَا الْفَلَاحُ. قَالَ قُلْتُ: وَمَا الْفَلَاحُ؟ قَالَ: السَّحُورُ. ثُمَّ لَمْ يَقُمْ بِنَا بَقِيَّةَ الشَّهْرِ. رَوَاهُ أَبُو دَاوُدَ وَالتِّرْمِذِيُّ وَالنَّسَائِيُّ وَرَوَى ابْنُ مَاجَهْ نَحْوَهُ إِلَّا أَنَّ التِّرْمِذِيَّ لَمْ يَذْكُرْ: ثُمَّ لَمْ يَقُمْ بِنَا بَقِيَّة الشَّهْر