Prayers for the souls of the dead to go to a better spirit world (“heaven” rather than “hell”) are a universal feature of almost all world religions. They are also common in the popular Christianity – derived from medieval Christanity – that believes in immortal souls.
However, in the Bible the dead are dead, so there is nothing further that can be done to interceded for them. And there is no example of praying for any dead person in the Bible. The attitude of the Bible is typified by King David’s response to his servants after long fasting and praying failed to save the life of his child with Bathsheba:
” But now he is dead. Why should I fast? Can I bring him back again? I shall go to him, but he will not return to me.” (1 Samuel 1:23)
Having said that, prayers thanking God for the life of a man or woman, prayers for his or her family, and prayer to all be reunited at the return of Christ at the resurrection are completely appropriate at a funeral service.