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 ﷺ قال: "لو أن أحدكم إذا أتى أهله قال: بسم الله، اللهم جنبنا الشيطان وجنب الشيطان ما رزقتنا، فقضى بينهما ولد لم يضره " ((متفق عليه)).