Praise be to Allah, and peace and blessings be upon the Messenger of Allah. To proceed:
The basic principle is that an oath should only be made by Allah Almighty or by one of His attributes. It is not permissible for a Muslim to swear by a created being, such as the Prophet ﷺ, one’s father, the Kaaba, or anything else.
The Prophet ﷺ said:
“Whoever is going to swear, let him swear by Allah or remain silent.”
Narrated by Al-Bukhari.
He ﷺ also said:
“Whoever swears by other than Allah has committed disbelief or shirk.”
Narrated by Abu Dawud and At-Tirmidhi.
Therefore, if a person says, “I ask you by your father,” intending it as an oath by the father, or says, “I ask you by Allah and the Prophet,” intending it as an oath, this is not permissible because he has combined Allah Almighty with someone else in an oath.
Scholars have differed regarding this expression. Many regarded it as a prohibited form of oath, while some scholars understood it in another sense: reminding a person of the rights of kinship and maintaining family ties, rather than swearing by kinship itself.
According to this interpretation, when a person says to a relative, “I ask you by the kinship between us,” he means: I remind you of the rights arising from our family relationship and of your duty to uphold the ties of kinship that Allah has commanded.
This is similar to saying: “I remind you of the kinship between us,” or “I appeal to you by our family ties.”
Allah Almighty says:
“And fear Allah, through whom you ask one another, and the wombs. Indeed Allah is ever, over you, an Observer.”
[An-Nisa 4:1]
There are different Qur’anic readings and interpretations concerning this verse.
According to the reading of the majority, in which “al-arhama” is in the accusative case, the meaning is: Fear Allah, and beware of severing the ties of kinship.
There is also a reading in which “al-arhami” is in the genitive case. Scholars have offered several explanations for this, including that it refers to the way people used to appeal to one another by kinship, or that it means reminding others of the rights of kinship rather than swearing by it.
Therefore, this verse should not be taken as a general proof that swearing by created beings is permissible.
A distinction should be made between words intended as an oath by kinship and words intended merely to remind a relative of the rights arising from family ties.
The first falls under swearing by other than Allah and is prohibited.
As for the second, such as saying to a relative, “I ask you by the rights of the kinship between us to help me,” intending to remind him of the duty of maintaining family ties, some scholars have permitted it when understood in this sense, because family ties have rights established by Islamic law that must be observed.
This concerns matters between people themselves, and should not be confused with the separate issue of seeking a means of approach to Allah in supplication.
Swearing by other than Allah Almighty is not permissible, whether by the Prophet ﷺ, one’s father, or any other created being.
As for saying, “I ask you by kinship,” scholars have differed. If the intention is to swear by kinship, then it is prohibited. If the intention is to remind a relative of the rights of family ties and kinship, some scholars have permitted it with this meaning.
It is better to use clear expressions that cannot be understood as swearing by other than Allah, such as saying:
“I remind you by Allah and by the rights of the kinship between us to maintain your family ties,” or similar expressions.
And Allah knows best.