Prayer and chanting help connect with the higher and gives temporary relief. The intonation of the chants calms the mind for the time being. However, for long-term stability and independence, study of the Bhagavad Gita gives knowledge which removes the grief and gives us understanding of life and death. However, wait till you recover from the grief as the mind may be too agitated for study at the moment. While imbibing the ideas make a note of the important ones and think about them through the day. Experiment with them. Pick one idea a day to practice. When you see it working you will be encouraged to practise them more until they become a default setting in you. You will then find the strength and the power to face challenges with ease.
We usually say “may his soul rest in peace” after death, and people believe that soul’s rest is directly proportional with the rules that his/her family members will follow after death, more strict we’re with these rules, soul will get more rest (according to everyone).
The rituals performed for the departed person are mainly for the family and not for the departed as wrongly believed. They give relief and comfort from the grief to the family.
Is it true in that way or we follow these rules only to protect ourselves? Is it the only way to pay tribute to his soul? Can our karma affect my father’s soul?
Anyone else’s karma or actions cannot affect your father’s soul. You can only get affected by your own karma or actions.