Is it possible to connect the saying "If Allah wills, may my hand be cut off if this happens," which is said to express the impossibility of something occurring, with the noble verse: (And [remember] when they said, "O Allah, if this is indeed the truth from You, then rain down upon us stones from the sky or bring us upon us a painful torment") [Al-Anfal/32], such that it is not permissible to utter such a saying?

It is not permissible to supplicate against oneself, whether the supplication is immediate or conditional, based on the Prophet's (peace be upon him) saying: "Do not supplicate against yourselves, nor against your children, nor against your possessions. You might coincide with an hour from Allah in which a request is made for a grant, and He responds to you." The phrases some people use to emphasize their words, such as supplicating against themselves, are neither an oath nor do they entail the ruling of an oath. Shaykh al-Islam Ibn Taymiyyah mentioned that there are only six types of oaths that entail a ruling, and this type is not among them. Furthermore, the noble verse: ﴿And when they said, "O Allah, if this is indeed the truth from You, then rain down upon us stones from the sky or bring upon us a painful torment"﴾ is a supplication and not an oath. Jurists have explicitly stated that supplicating against oneself is not considered an oath and does not entail expiation. Therefore, whoever supplicates against themselves in the manner mentioned, it is not considered an oath and only requires seeking forgiveness for committing that which is forbidden.