Musannaf Ibn Abi Shayba 21:612

Jarir ibn Abd al-Hamid narrated to us, from Mansur, from Salim, from Kurayb, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If one of you, when he intends to approach his wife, says: 'In the name of Allah, O Allah, keep Satan away from us and keep Satan away from what You provide us,' then if a child is decreed between them from that, Satan will never harm him."