Volume 8, Book 75, Number 397:
Narrated Ibn ‘Abbas:
The Prophet said, “If anyone of you, when intending to have a sexual intercourse with his wife,
says: ‘Bismillah, Allahumma jannibna-sh-shaitan, wa jannibi-sh-shaitan ma razaqtana,’ and if the
couple are destined to have a child (out of that very sexual relation), then Satan will never be able to
harm that child.”