Imam Al-Nawawi’s Riyad-us-Saliheen
Remembrance of Allah in all Conditions
Allah, the Exalted, says:
“Verily! In the creation of the heavens and the earth, and in the alternation of night and day, there are indeed signs for men of understanding. Those who remember Allah (always, and in prayers) standing, sitting, and lying down on their sides..” (3:190,191)
1444. `Aishah (May Allah be pleased with her) reported: The Messenger of Allah (sallallaahu alayhi wa sallam) used to remember Allah at all times.
1445. Ibn `Abbas (May Allah be pleased with them) reported: The Prophet (sallallaahu alayhi wa sallam) 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].