The Prophet ﷺ said, "If any of you, when he comes to his wife, says, 'In the name of Allah. Allah, keep Satan away from us and keep Satan away from what You have provided us,' then if Allah decrees a child between them, Satan will never harm that child."
حدثنا ابن أبي عمر حدثنا سفيان بن عيينة عن منصور عن سالم بن أبي الجعد عن كريب
قال النبي ﷺ لو أن أحدكم إذا أتى أهله قال بسم الله اللهم جنبنا الشيطان وجنب الشيطان ما رزقتنا فإن قضى الله بينهما ولدا لم يضره الشيطان
Sourced from a hadith agreed upon by Bukhari and Muslim. Bukhari narrated it in the Book of Nikah, chapter on what one should say when approaching one's spouse, hadith no. 5165, and Muslim narrated it as hadith no. 1434, both from the hadith of Mansur through this chain.