Any chants, mantras that are alien to him will only add to his confused state of mind if he is not Buddhist.
Please help your friend die in a good and happy state of mind. Where he can reflect on his good deeds and achievements in life so that he is reminded of the wholesome kamma he has made in his life.
Bhikkhu Aggacitta suggests in his book "Preparing the mind for death":
So, to further increase the chances of a good death, family members or close friends
could make preparations to create circumstances conducive to arousing wholesome neardeath
kamma. Some suggestions follow.
·Impress on the dying person that death is a natural phenomenon that everyone has to
go through and that it can be accepted without fear or resistance.
·Persuade and help the dying person to let go of all attachments to her beloved ones
and possessions, grudges against anyone, and remorse over anything that has or has not
been done. To this end, the dying person’s beloved ones should be told not to wail and
lament at her deathbed, for this may consolidate her attachments or grief.
·Provide the dying person with the opportunity to perform a good deed, e.g. listening
to Pàli chanting if he understands or appreciates it, listening to Dhamma talks, making a
donation on his behalf, encouraging him to mentally recite the Three Refuges
continuously as a mantra, or to engage in any wholesome meditation practice he is most
·Remind the dying person of her past meritorious deeds. One could keep a special
notebook where the dates and nature of significant meritorious deeds one has
performed are recorded. Someone could read the list to the dying one.
·Gather Dhamma friends around the dying person and radiate loving-kindness to him,
thinking: “May you be free from animosity, free from oppression, free from trouble, and
may you look after yourself with ease.”
Despite having lived an unethical and irreligious life, one could also die well and live
well in the next life if such fortuitous circumstances bring about a wholesome near-death
kamma. But of course, if you want the best assurance for a favourable hereafter, try to do
the utmost: live a morally upright and spiritually fulfilling life and associate with good
Dhamma friends who will be able to help create conditions conducive to a good death.
My thoughts are with you.