The Prophet ﷺ confided to me a secret which I did not disclose to anybody after him. And Um Sulaim asked me (about that secret) but I did not tell her.  

سَمِعْتُ أَنَسَ بْنَ مَالِكٍ أَسَرَّ إِلَىَّ النَّبِيُّ ﷺ سِرًّا فَمَا أَخْبَرْتُ بِهِ أَحَدًا بَعْدَهُ وَلَقَدْ سَأَلَتْنِي أُمُّ سُلَيْمٍ فَمَا أَخْبَرْتُهَا بِهِ