Is owning a guitar as a personal hobby, with a commitment not to use it in a group, and self-punishment by withdrawing it in case of misuse, considered haram?

It is not permissible to use the guitar, because it is among the forbidden musical instruments, due to the saying of the Prophet, peace and blessings be upon him: "There will be people from my Ummah who will consider lawful illicit sexual intercourse, silk, alcoholic beverages, and musical instruments." His saying "consider lawful" indicates that they were originally forbidden, but they made them permissible. The madhhab of the four Imams is that all musical instruments are forbidden. Mujahid interpreted Allah's saying: "And incite [to evil] whoever you can among them with your voice" (Quran 17:64) as referring to singing and musical instruments. Using and owning a guitar is forbidden, and its prohibition is not negated by the intention of amusement or individual use. A Muslim should avoid the steps of Satan and spend his time in beneficial knowledge and righteous deeds.