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].
App reference: Book 16, Hadith 38
Arabic/English book reference: Book 16, Hadith 1445