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." (Using translation from Bukhārī 141)   

النَّبِيَّ ﷺ قَالَ لَوْ أَنَّ أَحَدَهُمْ قَالَ حِينَ يُوَاقِعُ أَهْلَهُ «بِسْمِ اللهِ اللهُمَّ جَنَّبَنِي الشَّيْطَانَ وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا فَقُضِيَ بَيْنَهُمَا وَلَدٌ لَمْ يَضُرَّهُ الشَّيْطَانُ» خَالَفَهُ ابْنُ أَبِي عُمَرَ  

Ibn ‘Abbas reported the Prophet ﷺ as saying “If anyone who means to have intercourse with his wife says “In the name of Allaah, O Allaah, keep us away from the devil and keep the devil away from what You hast provided us.” It will be ordained that no devil will ever harm the child born to them. (Using translation from Abū Dāʾūd 2161)   

قَالَ رَسُولُ اللهِ ﷺ «لَوْ أَنَّ أَحَدَكُمْ إِذَا أَتَى أَهْلَهُ» قَالَ «بِسْمِ اللهِ اللهُمَّ جَنِّبْنِي الشَّيْطَانُ وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا ثُمَّ قُضِيَ بَيْنَهُمَا وَلَدٌ لَمْ يَضُرَّهُ الشَّيْطَانُ»