Is the mother obligated to financially support her son, even though he is 20 years old and works? And what are the conditions for this?

Filial piety and kindness to one's mother are among the best acts of drawing closer to Allah. If the mother is poor and the son is wealthy, it is obligatory for him to spend on her, by consensus.

However, if the son is poor, he is not obligated to spend on his mother or any other relatives. The obligation of maintenance requires three conditions:

1. That the person maintained is poor, having neither wealth nor income. 2. That the maintainer has more than what is sufficient for his own needs, based on the Prophet's (peace be upon him) saying: "Begin with yourself, then with those whom you are responsible for." 3. That the maintainer is an heir.