Do a smile at the time of death and the softening of the body indicate the absence of grave torment and the angels' tidings of Paradise? And does the Hadith: "He whom his belly kills is a martyr" apply to one who dies from liver, kidney, or lung disease, or from a belly filled with fluid? And do forgiveness and pardoning oppressors after their repentance save one from grave torment? And will one who is given tidings of Paradise not be tormented in the grave? And is seeking forgiveness better, or supplicating with "My Lord, protect him from the torment of the grave"?

Abandoning prayer and drinking alcohol are major sins, and one who repents from a sin is like one who has no sin. It is hoped that your father's repentance has been accepted and that Allah has forgiven his sins.

Your father may be rewarded with the recompense of one who dies from an abdominal illness (al-mabṭūn), and his forgiveness and clemency may be a cause for Allah's forgiveness of him.

Smiling after death may be a sign of a good ending, but it does not necessarily mean he has been given glad tidings of Paradise.

It is recommended to combine seeking forgiveness (istighfar) and supplicating (du'a) for the deceased in general, as the effect of both reaches them.

There is no text that prefers seeking forgiveness over supplicating for protection from the torment of the grave. Both are reported from the Prophet, peace and blessings be upon him.

Whoever has been given glad tidings of Paradise will not be tormented, for Allah, the Almighty, says: "Indeed, those who say, 'Our Lord is Allah,' and then remain steadfast - the angels will descend upon them, [saying], 'Do not fear and do not grieve but receive good tidings of Paradise, which you were promised.'"