In life, when we make a promise to somebody, we have to honour our promises no matter what or how. Only when a promise is honour then we can live life with pride and dignity. And if we happen to break our promises, we will have to carry the broken promises for the rest of our life in regret.

The same goes to believers who have or may have, in front of the deity, make promises to the deity but unfortunately pass on, and have not been able to honoured their promises. The surviving family members, on behalf of the deceased, will have to engage a Taoist priest to do prayer to the deity to honour the promises on behalf of the deceased.
So, how do we verify whether the deceased had made any promise to the deity? By right there isn’t. Unless you are aware beforehand that the deceased had made such promises to the deity or the deceased had requested for your help to honour the promises made before he or she passes on, there is no way to find out.
Therefore, the Taoist priest usually chants to honour the promise on behalf of the deceased followed by prayers to send off the deceased. This is to ensure that the deceased will not bear any burden that violates the promise and not able to leave peacefully.
替往生者还愿
在生活中,当我们向某人许下诺言时,无论如何,我们都必须兑现承诺。只有当承诺兑现时,我们才能自豪和有尊严地生活。而且,如果我们违背了承诺,我们将会抱憾地度过余生。

比如,有些信徒曾经或已经在神灵面前作出的承诺但很不幸的还没来得及兑现就去世。如没聘请道长诵经向神灵奉还承诺,去世的信徒将会带着违背了的承诺而无法好好的往生。
那么,我们如何知道去世了的家人是否有对神灵做出了承诺呢?除非您事先知道死者曾经对神灵做出了这样的承诺,或者死者曾请求您的帮助以奉还他或她逝世前的承诺,否则,你是无法知到答案。
所以,道长通常会替死者诵经向神灵奉还承诺,然后才开始诵经超度死者。这是为了确保死者不会承担任何违背承诺的包袱而导致无法好好的往生。