Sahih Muslim 1084 a
Jabir (Allah be pleased with her) narrated that the Prophet (ﷺ) separated himself from his wives for a month. (His wives said:
) He came to us on the twenty-ninth day, whereupon we said: It is the twenty-ninth (day) today. Thereupon he said: So far as the month is concerned, (and he, with a view to explaining it) flapped his hands thrice, but held back one finger at the last turn.
حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَخْبَرَنَا اللَّيْثُ، ح وَحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، - وَاللَّفْظُ لَهُ - حَدَّثَنَا لَيْثٌ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، - رضى الله عنه - أَنَّهُ قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم اعْتَزَلَ نِسَاءَهُ شَهْرًا فَخَرَجَ إِلَيْنَا فِي تِسْعٍ وَعِشْرِينَ فَقُلْنَا إِنَّمَا الْيَوْمُ تِسْعٌ وَعِشْرُونَ ‏.‏ فَقَالَ ‏
"‏ إِنَّمَا الشَّهْرُ ‏"‏ ‏.‏ وَصَفَّقَ بِيَدَيْهِ ثَلاَثَ مَرَّاتٍ وَحَبَسَ إِصْبَعًا وَاحِدَةً فِي الآخِرَةِ ‏.‏