Among the best of earnings
It was narrated from ‘Aa’isha (radi Allahu anha) that the Prophet (sal Allahu alaihi wa sallam) said: “Among the best of that which a man consumes is what he earns (by his own efforts), and his son is part of that which he earns.”
[Sunan Abu Dawud - Classed as Sahih by Sh al-Albaani]
The child – male or female – is obliged to spend on his (or her) parents if they are poor and he is rich. The obligation of spending on them is indicated by the Qur’an, Sunnah and scholarly consensus (ijmaa’).
Allah says (interpretation of the meaning): “And your Lord has decreed that you worship none but Him. And that you be dutiful to your parents” [Al-Isra’ 17: 23]
Being dutiful includes spending on them if they are in need.
Ibn al-Mundhir (may Allah have mercy upon him) said: The scholars are unanimously agreed that spending on poor parents who have no income or wealth is an obligation on the child’s wealth.
It is obligatory to also spend on grandfathers and grandmothers on the father’s side and on the mother’s. This is the view of the majority of scholars (including the three imams, Abu Haneefah, al-Shaafa’i and Ahmad), because the grandfather is also called a “father”.
Allah says (interpretation of the meaning): “It is the religion of your father Ibraaheem (Abraham)” [Al-Hajj 22: 78]
And Allah says (interpretation of the meaning): “And marry not women whom your fathers married” [al-Nisa’ 4:22]
Here “fathers” includes the father and the grandfather on both the father’s and mother’s side.
And Allah says (interpretation of the meaning): “For parents, a sixth share of inheritance to each if the deceased left children” [al-Nisa’4:11]
Here “parents” includes both the grandfather and the grandmother.
The grandmother is also called a mother.
Allah says (interpretation of the meaning): “Forbidden to you (for marriage) are: your mothers” [al-Nisa’ 4:23]
This includes the mother and grandmother, according to scholarly consensus.
As the grandfather is called a “father” and the grandmother is called a “mother”, they are included in the evidence which indicates that it is obligatory to be dutiful towards one’s parents and spend on them.
Ibn ‘Uthaymeen (may Allah have mercy upon him) said in al-Sharh al-Mumti’ (in the chapter on spending on relatives): The ascendants are those from whom you stem of fathers and mothers.
The descendants are those who stem from you of sons and daughters.
Then he said: It should be noted that this topic is like the topic of prohibition of marriage, and there is no difference between the father’s side and the mother’s side. The ascendants and descendants are the same, whether they are relatives on the mother’s side or relatives on the father’s side. You are obliged to spend on them, but that is subject to conditions.
In order for it to be obligatory to spend on fathers and grandfathers, they should be poor and the child should be rich, because the Prophet (sal Allahu alaihi wa sallam) said: “Start with yourself and give charity to yourself. If there is anything left over, then (give) to your family. If there is anything left over from your family, then (give) to your relatives.” [Sahih Muslim]
And Allah knows best!