The ruling on one who is lax in fasting as expiation for accidental killing

The question: The questioner (Sa'd N. A. Al-Dosari) from Riyadh says: A relative of mine accidentally hit a young girl with his vehicle, and the girl passed away. He was required to fast for two consecutive months, but he has not fasted to this day. When we tell him to fast, he says: [Al-Baqarah: 173]. What should we do with him? Please note that he is a young man capable of fasting, currently eighteen years old, i.e., an adolescent. Should his guardian fast on his behalf for that, and will he be rewarded?
The answer: It is obligatory for him to fast. He should be told: "Indeed, Allah is Forgiving and Merciful" [Al-Baqarah: 173], and also severe in punishment. Allah the Exalted said: [Al-Hijr: 49] [Al-Hijr: 50]. And He, the Exalted, said: [Ghafir: 3]. He is "the Forgiver of sin, the Acceptor of repentance" for the one who repents, turns back, and remains steadfast, and "severe in punishment" for the one who defies the command of Allah and disobeys His command, Blessed and Exalted is He. Therefore, it is obligatory to be cautious. "Inform My servants" means: inform them. "That I am the Forgiving, the Merciful" means: for the one who repents to Him and remains steadfast in His obedience. "And that My punishment is the painful punishment" for the one who disobeys and defies Him.
So, upon the one who kills a girl or anyone else accidentally, or with quasi-intention, is the expiation: freeing a slave. If he is unable, he must fast for two consecutive months, sixty days. If he is unable due to illness until Allah heals him, he fasts. He is eighteen years old, an adult; it is not permissible for him to be lax in this. He must be advised. Yes.
The presenter: May Allah reward you, Your Eminence the Shaykh.