(The Prophet) Solomon son of (the Prophet) David said, "Tonight I will go round (i.e. have sexual relations with) one hundred women (my wives) everyone of whom will deliver a male child who will fight in Allah's Cause." On that an Angel said to him, "Say: 'If Allah will.' " But Solomon did not say it and forgot to say it. Then he had sexual relations with them but none of them delivered any child except one who delivered a half person. The Prophet ﷺ said, "If Solomon had said: 'If Allah will,' Allah would have fulfilled his (above) desire and that saying would have made him more hopeful."
لَهُ الْمَلَكُ قُلْ إِنْ شَاءَ اللَّهُ فَلَمْ يَقُلْ وَنَسِيَ فَأَطَافَ بِهِنَّ وَلَمْ تَلِدْ مِنْهُنَّ إِلاَّ امْرَأَةٌ نِصْفَ إِنْسَانٍ قَالَ النَّبِيُّ ﷺ لَوْ قَالَ إِنْ شَاءَ اللَّهُ لَمْ يَحْنَثْ وَكَانَ أَرْجَى لِحَاجَتِهِ