The Messenger of Allah ﷺ asked a man: Did you fast the last day of Sha'ban ? He replied: No. He said: If you did not observe a fast, you must fast for a day. One of the two narrators said: For two days. (Using translation from Abū Dāʾūd 2328)   

أَنَّ رَسُولَ اللهِ ﷺ قَالَ لِرَجُلٍ «هَلْ صُمْتَ مِنْ سُرَرِ شَعْبَانَ شَيْئًا؟» قَالَ لَا قَالَ «إِذَا أَفْطَرْتَ فَصُمْ يَوْمَيْنِ» وَقَالَ الْجُرَيْرِيُّ فَصُمْ  

[Machine] "The Messenger of Allah ﷺ said to him, 'Have you observed anything in secret during this month?' He said, 'No.' He said, 'Then if you break your fast or the people break their fast, fast for two days.' 'Amr said that Yahya narrated twice from Muttarrif that the Prophet ﷺ said to 'Imran: 'Inform us.' 'Amr bin 'Ali said: Muhammad bin 'Abdul-'Ala informed us, from Al-Mu'tamir, from his father, from Abu Al-'Ala', from Muttarrif, similar to this. 'Abu Al-'Ala' said: The Messenger of Allah ﷺ said to a man, so he mentioned something similar to this. So I said to him: 'From whom did you hear this?' He said: 'I asked a man from his household, from whom did you hear this?' So the man said: 'From 'Imran bin Husain, from the Messenger of Allah ﷺ .' "  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ لَهُ «صُمْتَ مِنْ سَرَرِ هَذَا الشَّهْرِ شَيْئًا؟» قَالَ لَا قَالَ «فَإِذَا أَفْطَرْتَ أَوْ أَفْطَرَ النَّاسُ فَصُمِ يَوْمَيْنِ» قَالَ عَمْرٌو حَدَّثَنَا يَحْيَى مَرَّتَيْنِ مَرَّةً عَنْ مُطَرِّفٍ أَنَّ النَّبِيَّ ﷺ قَالَ لِعِمْرَانَ 2883 أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ قَالَ حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ عَنِ التَّيْمِيِّ عَنْ أَبِي الْعَلَاءِ عَنْ مُطَرِّفٍ عَنْ عِمْرَانَ نَحْوَهُ 2884 أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الْأَعْلَى قَالَ حَدَّثَنَا الْمُعْتَمِرُ عَنْ أَبِيهِ قَالَ حَدَّثَنَا أَبُو الْعَلَاءِ بْنُ الشِّخِّيرِ أَنَّ رَسُولَ اللهِ ﷺ قَالَ لِرَجُلٍ فَذَكَرَ نَحْوَهُ فَقُلْتُ لَهُ عَمَّنْ يُحَدِّثُ هَذَا أَبُو الْعَلَاءِ؟ قَالَ سَأَلْتُ رَجُلًا مِنْ أَهْلِ بَيْتِهِ عَمَّنْ يُحَدِّثُ هَذَا أَبُو الْعَلَاءِ؟ فَقَالَ الرَّجُلُ عَنْ عِمْرَانَ بْنِ حُصَيْنٍ عَنْ رَسُولِ اللهِ ﷺ