Praise be to Allah.
The highest number of wives of Sulaymaan (peace be upon him) that is mentioned in the saheeh ahaadeeth is one hundred, as was narrated by al-Bukhaari in his Saheeh (5242) from Abu Hurayrah who said: “Sulaymaan ibn Dawood (peace be upon them both) said: ‘Tonight I will go around to one hundred women, each of whom will give birth to a boy who will fight for the sake of Allaah.’ The angel said to him, ‘Say in sha Allaah (if Allaah wills).’ But he did not say it, as he forgot. He went around to them but none of them gave birth, apart from one woman who gave birth to half a child. The Prophet (peace and blessings of Allaah be upon him) said: ‘If he had said in sha Allaah, he would not have broken his oath and he would have had more hope of fulfilling his wish.’” (Narrated by Muslim, 1654). According to another report narrated by Muslim, he said ninety women. According to a mu’allaq report narrated by al-Bukhaari in his Saheeh, in the Chapter on seeking a son for jihad (Man talaba al-walad li’l-Jihaad), he said ninety-nine women.
Perhaps the one who said one hundred was rounding up the figure, and the one who said ninety was rounding it down, as was suggested by al-Haafiz ibn Hajar in his commentary on this hadeeth.
But al-Haafiz ibn Hajar narrated in his story of Sulaymaan (peace be upon him) in al-Bidaayah wa’l-Nihaayah, vol. 2, from many of the salaf, that the number of Sulaymaan’s wives was one thousand. Al-Haafiz ibn Hajar said likewise in Fath al-Baari, in his commentary on hadeeth no. 3424.
This number was narrated from the Children of Israel [i.e., the Jews], so we neither believe it nor disbelieve it. There is nothing in the ahaadeeth quoted above to either prove or disprove that.
With regard to the reason for that, Allaah gives to those whom He wills among His slaves whatever He wills of worldly power and enjoyment. This is according to His great wisdom and grace. He is not to be questioned about what He does, may He be glorified and praised. He gave to Sulaymaan exclusively great power which He did not give to anyone after him. So it is not far-fetched to suggest that He also gave him this great strength which enabled him to marry this number of women. It should not cross the mind of any Muslim that this matter implies any form of belittlement towards this Prophet, rather it is a reflection of his perfect power, virtue and manhood, and thus he hoped that Allaah would bless him, in a single night, with one hundred sons, all of whom would go out as knights, fighting for the sake of Allaah. But first and last we must believe that Allaah creates whatever He wills and chooses, and none can overturn His ruling or ward off His decree.
And Allaah knows best.