Is expiation incumbent upon one who caused an accident in which his father and the driver of another car died, while he is certain that he was not at fault, or that the percentage of fault does not exceed 25%? And does he inherit from his father in this case?

If specialists determine that you are entirely at fault for the accident that led to the death of your father and the other car's driver, then the following is incumbent upon you:

1. Expiation for Accidental Killing (Kaffarat Qatl al-Khata’): Two expiations are required, one for each soul. This involves freeing a believing slave; if one cannot be found, then fasting for two consecutive months for each expiation, based on the Almighty's saying: ﴿And it is not for a believer to kill a believer except by mistake. And whoever kills a believer by mistake – then freeing a believing slave and a compensation payment presented to his family, unless they remit it as charity... And he who does not find [one] – then a fast for two consecutive months as repentance from Allah. And Allah is ever Knowing and Wise.﴾ (An-Nisa: 92).

2. Blood Money (Diyya): For each soul, it is obligatorily due from your 'Aqilah (agnatic relatives) by consensus. If the 'Aqilah are unable to pay, the Muslim treasury (Bayt al-Mal) bears it. If it is not possible to take it from the treasury, there is a difference of opinion on the matter, and the Hanbali school holds that nothing is incumbent upon the killer, while the majority opinion is that it is incumbent upon the killer himself. If the heirs of the deceased pardon the blood money, it is waived.

3. Inheritance: The majority of scholars hold that the killer does not inherit anything from the slain, even if the killing was accidental, based on the hadith: "The killer does not inherit anything." This is the view of Imam Ahmad, Ash-Shafi'i, and Abu Hanifa. Imam Malik and a group of scholars held that the accidental killer inherits from the slain's wealth, but not from his blood money, and some later scholars have adopted this view.

If the heirs do not agree, the case should be referred to the Sharia court for judgment.