All perfect praise be to Allah the Lord of the Worlds. May Allah`s peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

Ḥadd Allāh: The singular is Ḥadd. The Ḥudūd Allāh are His prohibitions that He has forbidden committing or violating. Allah, the Exalted, says {what means}: "These are the limits of Allah, so do not approach them." [Al-Baqarah/187].

The statement of a person: "Ḥadd Allāh," or "'Ahd Allāh" (The Covenant of Allah), or "Allāh is between me and you" are considered figurative expressions of an oath (Kināyāt al-Yamīn).

• If the speaker intended it as an oath, then it is an oath.

• If the speaker did not intend it as an oath, then it is not considered an oath.

Shaykh al-Islām Imam Al-Nawawī (may Allah have mercy on him) said: "If he said: 'By the Covenant of Allah, and the Testament of Allah, and the Trust of Allah,' Al-Mutawallī said: 'If he intended the oath, then it is an oath. If he used it generally [without specific intent], then it is not.'" (Rawḍat aṭ-Ṭālibīn, Vol.11/P.16).

Imam Sulaymān al-Jamal ash-Shāfi'ī (may Allah have mercy on him) said: "If he said 'Allah' for example... 'I will certainly do such-and-such,' it is a figurative expression, like his saying: 'I bear witness by Allah,' or 'By the life of Allah,' or 'Upon me is the Covenant of Allah, His Testament, His Liability, His Trust, and His Guarantee that I will certainly do such-and-such.' If he intended the oath by it, then it is an oath; otherwise, it is not," meaning, it takes the ruling of an oath if he meant it as one. (Futūḥāt al-Wahhāb, 5/292).

As for swearing an oath upon another person: When someone swears an oath upon another, it is recommended (Mustaḥabb) for the latter to fulfill the oath. If the person addressed does not do what was requested, the ruling depends on the intention of the one who swore the oath (the speaker):

• If the speaker intended the oath as an affirmation for himself and an emphasis on fulfilling this matter and obligating the other person to it, the speaker must pay the expiation for breaking his oath (Kaffārat al-Ḥinth).

• If the speaker intended by his oath the oath of the person being addressed (e.g., intending to make the addressed person swear by Allah), or intercession/pleading with him by Allah, or if he had no specific intention of an oath, then it is not an oath, and neither the swearer nor the addressed person owes anything.

Imam Al-Shirbīnī (may Allah have mercy on him) said: "If a person says to another: 'I insist upon you by Allah,' or 'I ask you by Allah that you must do such-and-such,' and he intended his own oath, then it is an oath, due to its fame on the tongues of the Muslims. It is recommended for the addressed person to fulfill it if the fulfillment does not involve committing something prohibited or disliked. If he does not fulfill it, the expiation is required from the one who swore the oath. Otherwise (i.e., if he intended the oath of the addressed person, or intended no oath but merely pleading, or used the expression generally), then it is not an oath in these three scenarios, because neither he nor the addressed person swore an oath, and it is interpreted as pleading for the action." (Mughni al-Muḥtāj, Vol.6/P.186).

In conclusion, the phrase "Ḥadd Allāh" is a figurative expression of an oath.

• If you intended it as an oath, then it is an oath, and if the condition is broken, you must pay the expiation for breaking an oath.

• If you did not intend it as an oath, then it is not an oath, and you are cleared from the liability.

In the case of swearing upon another, if you intended to swear and emphasize your own obligation/request, it is an oath, and the expiation is required from you if the condition is broken. If you did not intend an oath, or intended the person being addressed to swear, it is not considered an oath, and no expiation is mandatory. In all cases, it is recommended for the addressed person to fulfill your request to honor your oath. And Allah the Almighty knows best.