Praise be to Allah, and peace and blessings be upon the Messenger of Allah and his family.
Firstly:
We offer our condolences to this mother, and we ask Allah, may He be exalted, to guide her and her son, and to inspire him to follow the right path.
Secondly:
This poor mother has nothing to do with whether her son is guided or goes astray, and none of his sin is on her. Each individual is responsible for his own deeds and will be brought to account for them.
Allah, may He be exalted, says (interpretation of the meaning):
“Whoever is guided is only guided for [the benefit of] his soul. And whoever errs only errs against it. And no bearer of burdens will bear the burden of another”
[al-Israa’ 17:15]
“And no bearer of burdens will bear the burden of another. And if a heavily laden soul calls [another] to [carry some of] its load, nothing of it will be carried, even if he should be a close relative”
[Faatir 35:18].
Shaykh as-Sa‘di (may Allah have mercy on him) said:
“And no bearer of burdens will bear the burden of another” i.e., on the Day of Resurrection, each person will be requited for his deeds, and no person will carry the sins of another. “And if a heavily laden soul calls [another]” i.e., if a person who is heavily laden with sins and transgressions calls upon someone else to carry some of his burden, “nothing of it will be carried, even if he should be a close relative”; he will not be able to carry some of the burden of his relative. The hereafter is not like this world, in which a person can help his close friend; rather on the Day of Resurrection, a person will wish that he had some rights over other people, even over his parents and relatives.
End quote from Tafseer as-Sa‘di (p. 687).
It was narrated by at-Tirmidhi (2159), who classed it as saheeh, from ‘Amr ibn al-Ahwas, who said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say to the people during the Farewell Pilgrimage: “No one commits a sin but he does so to his own detriment, and no sinner commits a sin to the detriment of his child, or any child to the detriment of his parent.”
Also classed as saheeh by al-Albaani in Saheeh Sunan at-Tirmidhi.
Abu Dawood (4495) narrated that Abu Rimthah said: I went to the Prophet (blessings and peace of Allah be upon him) with my father, then the Prophet (blessings and peace of Allah be upon him) said to my father: “Is this your son?” He said: Yes, by the Lord of the Ka’bah. He said: “Is it true?” He said: I bear witness to it. The Messenger of Allah (blessings and peace of Allah be upon him) smiled at my resemblance to my father and my father’s oath concerning me, then he said: “He does not commit any sin to your detriment and you do not commit any sin to his detriment.” And the Messenger of Allah (blessings and peace of Allah be upon him) recited the verse: “and no bearer of burdens will bear the burden of another” [al-An‘aam 6:164].
Classed as saheeh by al-Albaani in Saheeh Sunan Abi Dawood.
Al-Qaari (may Allah have mercy on him) said in Mirqaat al-Mafaateeh (6/2272):
“He does not commit any sin to your detriment” means: you will not be brought to account for his sin, and “and you do not commit any sin to his detriment” means: he will not be brought to account for your sin. End quote.
So there is no blame on this mother for her son’s sin, but she must continue to advise him and exhort him, and she should show him that she dislikes the path that he is on. If her cutting off ties with him will have an impact on him and bring him back to his senses, then she should cut off ties with him, out of mercy and compassion towards him.
And Allah knows best.