Is it obligatory for two employed brothers, each earning a monthly salary of 20,000 Saudi Riyals, to financially support their widowed mother, who only possesses 1,500 Saudi Riyals per month, with a specified allowance, and what is the approximate amount of the allowance their mother is entitled to receive from her son's salary of 20,000 Saudi Riyals per month, especially the unmarried brother?

Children are not obligated to allocate a portion of their salaries to their mother, unless she is poor and in need of financial support. In that case, her maintenance becomes obligatory upon them, to be shared among them according to their means. The maintenance should be sufficient for her needs, including bread, condiments, clothing, and housing, according to custom. However, if the mother is wealthy, her maintenance is not obligatory upon her children, but she is permitted to take from their wealth what does not harm them or what they do not need. Giving charity to one's mother is among the best acts of devotion and obedience.