Inability to fast as Kaffarah for involuntary manslaughter
If the reality is as you have mentioned, it is obligatory for you to offer
the Kaffarah (expiation) of involuntary manslaughter, which is to free a believing bondsman or to fast two successive months. If you cannot afford the cost of freeing a believing bondsman, feeding, clothing or the like are not acceptable in this case, for Allah (Exalted be He) states:
...and whosoever kills a believer by mistake, (it is ordained that) he must set free a believing slave
to His Statement:
And whoso finds this (the penance of freeing a slave) beyond his means, he must fast for two consecutive months in order to seek repentance from Allâh. And Allâh is Ever All-Knowing, All-Wise.
Allah (Glorified be He) only prescribes freeing a bondsman or fasting for two consecutive months as a Kaffarah for involuntary manslaughter. For your Lord is never forgetful. However, whoever is unable to do this and their condition continues to prevent them, Allah knows their sincerity and willingness to fulfill His commands.Thus, He will forgive them. (Part No. 21; Page No. 296) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.