كتاب النكاح
16
The Book of Marriage
(18)
Chapter: What it is recommended to say when having intercourse
(18)
باب مَا يُسْتَحَبُّ أَنْ يَقُولَهُ عِنْدَ الْجِمَاعِ ‏

Ibn" Abbas (Allah be pleased with thern) reported that Allah's Messenger (ﷺ) said:

If anyone amongst you intends to go to his wife he should say: In the name of Allah,0 Allah protect us against Satan and keep away the Satan from the one that you have bestowed upon us, and if He has ordained a male child for them, Satan will never be able to do any harm to him.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ، - وَاللَّفْظُ لِيَحْيَى - قَالاَ أَخْبَرَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ سَالِمٍ، عَنْ كُرَيْبٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ لَوْ أَنَّ أَحَدَهُمْ إِذَا أَرَادَ أَنْ يَأْتِيَ أَهْلَهُ قَالَ بِاسْمِ اللَّهِ اللَّهُمَّ جَنِّبْنَا الشَّيْطَانَ وَجَنِّبِ الشَّيْطَانَ مَا رَزَقْتَنَا فَإِنَّهُ إِنْ يُقَدَّرْ بَيْنَهُمَا وَلَدٌ فِي ذَلِكَ لَمْ يَضُرَّهُ شَيْطَانٌ أَبَدًا ‏"‏‏.‏
Reference : Sahih Muslim 1434 a
In-book reference : Book 16, Hadith 136
USC-MSA web (English) reference : Book 8, Hadith 3361
  (deprecated numbering scheme)