What is the ruling on Salat al-Gha'ib (funeral prayer in absentia), and is it permissible to dedicate the reward of good deeds to the deceased, and what should I do to atone for having ill thoughts about a deceased Muslim sister?

We ask Allah the Almighty to have mercy on your friend and all deceased Muslims, and to grant you patience in her loss. It was narrated from Abu Hurayrah that the Messenger of Allah, peace and blessings be upon him, said: "Allah the Almighty says: 'There is no reward for My believing servant with Me, if I take his beloved one from the people of the world and he bears it with patience, except Paradise.'" (Narrated by Al-Bukhari). "His beloved one" refers to a loved one such as a child, a sibling, or anyone whom a person loves. "Bears it with patience" means to endure the loss with patience, hoping for reward from Allah.

The funeral prayer in absentia (Salat al-Gha'ib) is legislated for one who dies in a land where there is no one to pray over him.

The prayers of the living for the dead and the dedication of the reward of good deeds to them benefit the deceased, and the reward reaches them.

Sheikh Ibn Uthaymeen holds the view that it is permissible to dedicate the reward of deeds to the deceased, but it is preferable to stick to supplicating and seeking forgiveness for the deceased.

Avoiding ill-suspicion is obligatory, as Allah the Almighty says: "O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin." (Al-Hujurat: 12). What passes through one's mind in terms of thoughts, without speaking or acting upon them, is forgiven, as the Prophet, peace and blessings be upon him, said: "Indeed, Allah has forgiven my Ummah for what they talk to themselves about, as long as they do not speak of it or act upon it." (Narrated by Al-Bukhari and Muslim). The expiation for ill-suspicion that has not turned into a statement or action is through repentance and seeking forgiveness, and praying for and seeking forgiveness for your friend is better for both you and her.