The Prophet ﷺ said, "If anyone of you on having sexual relations with his wife said (and he must say it before starting) 'In the name of Allah. O Allah! Protect us from Satan and also protect what you bestow upon us (i.e. the coming offspring) from Satan, and if it is destined that they should have a child then, Satan will never be able to harm that offspring."  

يَبْلُغُ بِهِ النَّبِيَّ ﷺ قَالَ لَوْ أَنَّ أَحَدَكُمْ إِذَا أَتَى أَهْلَهُ قَالَ بِسْمِ اللَّهِ اللَّهُمَّ جَنِّبْنَا الشَّيْطَانَ وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا فَقُضِيَ بَيْنَهُمَا وَلَدٌ لَمْ يَضُرَّهُ