عَنِ ابْنِ عَبَّاسٍ ـ رضى اللہ عنهما ـ قَالَ قَالَ النَّبِيُّ صلى اللہ عليه وسلم: لَوْ أَنَّ أَحَدَهُمْ إِذَا أَرَادَ أَنْ يَأْتِيَ أَهْلَهُ قَالَ بِاسْمِ اللہ، الّٰلہُمَّ جَنِّبْنَا الشَّيْطَانَ، وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا، فَإِنَّهُ إِنْ يُقَدَّرْ بَيْنَهُمَا وَلَدٌ فِي ذَلِكَ، لَمْ يَضُرَّهُ شَيْطَانٌ أَبَدًا.
It is narrated by Hazrat Ibn ‘Abbasra that, “The Holy Prophetsa said, ‘When one of you intends to approach his spouse intimately, if he says: ‘Bismillah, Allahumma jannibna sh-shaytan, wa jannibi sh-shaytana ma razaqtana,’ [In the name of Allah, O Allah, protect us from Satan, and keep Satan away from the blessings You bestow upon us], then, should a child be ordained for them in that instance, Satan will not be able to harm the child ever.’”
(Sahih al-Bukhari, Kitab ad-du‘awat, Bab ma yaqulu idha ata ahlah, Hadith 6388)