Sahih Muslim 150
Sahih Muslim · Book 1: The Book of Faith · Being kind to one for whose faith there is concern because it is weak; Prohibition of attributing Faith to someone without definitive evidence
The same hadith has been narrated on the authority of Muhammad b Sa'd and these words (are also there):
وَحَدَّثَنَا الْحَسَنُ الْحُلْوَانِيُّ ، حَدَّثَنَا يَعْقُوبُ ، حَدَّثَنَا أَبِي ، عَنْ صَالِحٍ ، عَنْ إِسْمَاعِيلَ بْنِ مُحَمَّدٍ ، قَالَ سَمِعْتُ مُحَمَّدَ بْنَ سَعْدٍ ، يُحَدِّثُ هَذَا فَقَالَ فِي حَدِيثِهِ فَضَرَبَ رَسُولُ اللَّهِ صلى الله عليه وسلم بِيَدِهِ بَيْنَ عُنُقِي وَكَتِفِي ثُمَّ قَالَ " أَقِتَالاً أَىْ سَعْدُ إِنِّي لأُعْطِي الرَّجُلَ " .
The Messenger of Allah (ﷺ) gave a stroke on my neck or between my two shoulders and said: Sa'd, do you fight with me simply because I gave (a share) to a man?