كتاب الأذكار
16
The Book of the Remembrance of Allah
Ibn 'Abbas (May Allah be pleased with them) reported:
The Prophet (ﷺ) said, "If anyone intends to have (sexual intercourse) with his wife, he should say: "Bismillah! Allahumma janibnash-Shaitana, wa jannibish-Shaitana ma razaqtana (In the Name of Allah, O Allah! Keep us away from Satan and keep Satan away from what You have bestowed upon us);' and if Allah has ordained a child for them, Satan will never harm him."

[Al-Bukhari and Muslim].

وعن ابن عباس رضي الله عنهما عن النبي صلى الله عليه وسلم قال‏:‏ ‏ "‏لو أن أحدكم إذا أتى أهله قال‏:‏ بسم الله، اللهم جنبنا الشيطان وجنب الشيطان ما رزقتنا، فقضى بينهما ولد لم يضره ‏"‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏
Sunnah.com reference : Book 16, Hadith 38
Arabic/English book reference : Book 16, Hadith 1445