حَدَّثَنَا هَدَّابُ بْنُ خَالِدٍ، حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ ثَابِتٍ، عَنْ مُطَرِّفٍ، - وَلَمْ أَفْهَمْ مُطَرِّفًا مِنْ هَدَّابٍ - عَنْ عِمْرَانَ بْنِ حُصَيْنٍ، - رضى الله عنهما - أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ لَهُ أَوْ لآخَرَ " أَصُمْتَ مِنْ سَرَرِ شَعْبَانَ " . قَالَ لاَ . قَالَ " فَإِذَا أَفْطَرْتَ فَصُمْ يَوْمَيْنِ " .
Did you fast in the middle of Sha'ban? He said: No. Thereupon he (the Holy Prophet) said: If you did not observe fast, then you should observe fast for two days.
Source: Sahih Muslim — repository translation · Imam Muslim ibn al-Hajjaj al-Naysaburi — authenticity/grade metadata requires independent source review · Sunnah.comAudio not available for the selected reciter.
Source: Sahih Muslim — repository arabic · Imam Muslim ibn al-Hajjaj al-Naysaburi · Sunnah.com