assalamoalikum
i just wanted to know what if mother of a son after his marriage ask the man & his wife to sleep in the same room & on the bed with his son. what is the ruling of islam on this?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The scholars stated that it is permissible for one of the Mahrams to stay overnight with the husband and wife, and they provided evidence for this that Ibn ‘Abbaas spent the night with his maternal aunt Maymoonah once when the Prophet spent the night with her, as reported by Al-Bukhari and Muslim. Therefore, it is permissible for a mother to ask her son to sleep with his wife and his son in one bed.

However, it should be noted that it is an obligation on the spouses when having sexual intercourse to be in a place where there is no one else with them. Ibn Al-Haaj said in “Al-Madkhal”: “If a husband wishes to have sexual intercourse with his wife, then the Sunnah is that no one else should be with him in the room, as when Ibn ‘Umar wished to have sexual intercourse with his wife, he used to put away his baby out of his room.”

Moreover, Ibn Qudaamah said: “A husband should not have sexual intercourse (with his wife) in a way that someone else may see them or hear them, and he should not kiss her or touch her (with desire) in front of the people.” For more benefit, please refer to Fatwa 92251.

Allaah Knows best.