Sahih Bukhari Volume 4, Book 56, Hadith 2820

وَقَالَ اللَّيْثُ حَدَّثَنِي جَعْفَرُ بْنُ رَبِيعَةَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ هُرْمُزَ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ ـ رضى الله عنه ـ عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ قَالَ سُلَيْمَانُ بْنُ دَاوُدَ ـ عَلَيْهِمَا السَّلاَمُ ـ لأَطُوفَنَّ اللَّيْلَةَ عَلَى مِائَةِ امْرَأَةٍ ـ أَوْ تِسْعٍ وَتِسْعِينَ ـ كُلُّهُنَّ يَأْتِي بِفَارِسٍ يُجَاهِدُ فِي سَبِيلِ اللَّهِ، فَقَالَ لَهُ صَاحِبُهُ إِنْ شَاءَ اللَّهُ‏.‏ فَلَمْ يَقُلْ إِنْ شَاءَ اللَّهُ‏.‏ فَلَمْ يَحْمِلْ مِنْهُنَّ إِلاَّ امْرَأَةٌ وَاحِدَةٌ، جَاءَتْ بِشِقِّ رَجُلٍ، وَالَّذِي نَفْسُ مُحَمَّدٍ بِيَدِهِ، لَوْ قَالَ إِنْ شَاءَ اللَّهُ، لَجَاهَدُوا فِي سَبِيلِ اللَّهِ فُرْسَانًا أَجْمَعُونَ ‏"‏‏.

Narrated By Abu Huraira : Allah's Apostle said, "Once Solomon, son of David said, '(By Allah) Tonight I will have sexual intercourse with one hundred (or ninety-nine) women each of whom will give birth to a knight who will fight in Allah's Cause.' On that a (i.e. if Allah wills) but he did not say, 'Allah willing.' Therefore only one of those women conceived and gave birth to a half-man. By Him in Whose Hands Muhammad's life is, if he had said, "Allah willing', (he would have begotten sons) all of whom would have been knights striving in Allah's Cause."