سنن النسائي

It was narrated from Abu Hurairah, who attributed it to the Prophet: "Sulaiman said: 'I will certainly go around to ninety women tonight, each of whom will bear a child who will fight in the cause of Allah.' It was said to him: 'Say: If Allah wills' but he did not say it. He went around to them but none of them bore a child except for one woman who bore half a person." The Messenger of Allah (ﷺ) said: "If he had said: 'If Allah wills,' he would not have broken his vow, and this would have been a means to help him to get what he wanted."