What is the criterion for distinguishing between an oath and emphasizing speech with phrases such as "by the Prophet" or "by your life," and does the common saying "by the Prophet" fall under the category of an oath, especially with evidence from the words of the Prophet, peace be upon him and his family, and the noble Companions, such as his saying: "Indeed, by your father, you will be informed of it" and "He has succeeded, by his father, if he speaks truthfully"?

It is not permissible to swear by other than Allah, as it is a form of polytheism (shirk) with Allah. Scholars have unanimously agreed that an oath must only be by Allah or His attributes, and they have unanimously agreed on prohibiting swearing by other than Him, because it is among the greatest forbidden acts. There is no consideration for what some later scholars said, that it is merely a disliking (karahat al-tanzih), as that is a false statement.

As for the narrations that seem to imply the permissibility of swearing by other than Allah, such as the Prophet's (peace be upon him) saying, "He has succeeded, by his father, if he is truthful," scholars have responded to them with several answers, including: 1. That these wordings are not preserved or have been corrupted from the phrase "by Allah." 2. That such wordings were uttered without the intention of an oath, but this answer is invalid because the prohibition is general and absolute. 3. That such expressions are intended for emphasis, not glorification, and this is more unsound than the previous one, because an oath is meant to glorify that by which one swears. 4. That this was in the early period and was later abrogated (naskh), and this is the truth. So, any narrations about swearing by other than Allah were before the abrogation and the prohibition of it.

This answer is supported by the hadith of Ibn Umar: "Indeed, Allah forbids you from swearing by your fathers. Whoever is to swear, let him swear by Allah or remain silent." And the hadith of Sa'd ibn Abi Waqqas: "I once swore by al-Lat and al-Uzza. The Prophet (peace be upon him) said: 'Say: There is no god but Allah, alone, without partner. Then spit to your left three times and seek refuge [in Allah], and do not repeat [it].'"

Based on this, the prohibition of swearing by other than Allah is the decisive (muhkam) ruling, and anything else is ambiguous (mutashabih) with possibilities, such as: 1. That it was before the prohibition. 2. That it was specific to the Messenger of Allah (peace be upon him). 3. That it is something uttered unintentionally.

Therefore, it is necessary to adhere to the decisive ruling and strive to avoid swearing by other than Allah, because it is shirk, and its danger is immense. Ibn Mas'ud (may Allah be pleased with him) said: "To swear by Allah falsely is more beloved to me than to swear by other than Him truthfully," because the sin of shirk is greater than the sin of a major transgression.