Sahih Bukhari Volume 8, Book 78, Hadith 6176

قَالَ سَالِمٌ فَسَمِعْتُ عَبْدَ اللَّهِ بْنَ عُمَرَ، يَقُولُ انْطَلَقَ بَعْدَ ذَلِكَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَأُبَىُّ بْنُ كَعْبٍ الأَنْصَارِيُّ يَؤُمَّانِ النَّخْلَ الَّتِي فِيهَا ابْنُ صَيَّادٍ، حَتَّى إِذَا دَخَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم طَفِقَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَتَّقِي بِجُذُوعِ النَّخْلِ، وَهْوَ يَخْتِلُ أَنْ يَسْمَعَ مِنِ ابْنِ صَيَّادٍ شَيْئًا قَبْلَ أَنْ يَرَاهُ، وَابْنُ صَيَّادٍ مُضْطَجِعٌ عَلَى فِرَاشِهِ فِي قَطِيفَةٍ لَهُ فِيهَا رَمْرَمَةٌ أَوْ زَمْزَمَةٌ، فَرَأَتْ أُمُّ ابْنِ صَيَّادٍ النَّبِيَّ صلى الله عليه وسلم وَهْوَ يَتَّقِي بِجُذُوعِ النَّخْلِ، فَقَالَتْ لاِبْنِ صَيَّادٍ أَىْ صَافِ ـ وَهْوَ اسْمُهُ ـ هَذَا مُحَمَّدٌ‏.‏ فَتَنَاهَى ابْنُ صَيَّادٍ‏.‏ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لَوْ تَرَكَتْهُ بَيَّنَ ‏"‏‏.‏

'Umar added: Later on Allah's Apostle and Ubai bin Ka'b Al-Ansari (once again) went to the garden in which Ibn Saiyad was present. When Allah's Apostle entered the garden, he started hiding behind the trunks of the date-palms intending to hear something from Ibn Saiyad before the latter could see him. Ibn Saiyad was Lying on his bed, covered with a velvet sheet from where his mumur were heard. Ibn Saiyad's mother saw the Prophet and said, "O Saf (the nickname of Ibn Saiyad)! Here is Muhammad!" Ibn Saiyad stopped his murmuring. The Prophet said, "If his mother had kept quiet, then I would have learnt more about him."