What must be done? Is expiation due from me or my son for our feeling of guilt regarding the death of the bird, and what should we do for Allah to forgive us if we were the cause of its death?

He who intentionally confines an animal with the purpose of harming it, and neither feeds nor waters it until it dies, commits a grave sin, for the Prophet, peace and blessings be upon him, said: «A woman entered Hell because of a cat which she tied up and neither fed nor released to eat from the vermin of the earth, until it died of starvation.»

However, if there was no intention to harm the bird, but it was found dead without any action causing its death, then there is no blame. And if its death resulted from the son forgetting to feed it, there is also no blame, as long as he was fulfilling its rights and did not neglect its care while it was entrusted to him. This would be considered an error or forgetfulness, for Allah, the Almighty, says: {And there is no blame upon you for that in which you have erred, but [only for] what your hearts intended}, and for the Prophet, peace and blessings be upon him, said: «Indeed, Allah has forgiven my Ummah for their mistakes, their forgetfulness, and what they are forced to do.» It is preferable to give charity or perform good deeds as expiation.