In this difficult time, we want to express our deepest condolences for the loss of your grandfather. It is commendable that you are seeking guidance to ensure you honor him respectfully. Firstly, it is important to address the concern about "bad luck." As believers, we do not put stock in superstitions such as "bad luck," but rather, we trust in the sovereignty of God and His guidance through the Holy Spirit and shape our lives and actions according to the gospel of Jesus Christ and the power of the Holy Spirit. When you give your grandfather a bath, do it as a request from your family to ensure your grandfather is cleansed in a God honoring way to be presented for his burial and not as a response to a ritual or superstitious activity.
Remember the words of the Psalmist: "Yea, though I walk through the valley of the shadow of death, I will fear no evil, for you are with me. Your rod and your staff, they comfort me" . God is with you in this trying time, and you do not need to fear any superstitions.
It is natural to feel emotional during this process. Grieving is a normal and necessary part of healing. As Jesus wept at the grave of Lazarus, so too can you express your sorrow. "Jesus wept" . Tears are not a sign of bad luck but a sign of love and loss. Be with your family to comfort and be comforted together.
Before you undertake this task, pray for strength and peace. You may find it helpful to pray Psalm 23 or another comforting passage from the Bible. You could simply say. "Lord and our Heavenly Father, I need your strength to perform my duty to prepare my grandfather for his burial. It may have been my grandfather's last wish for this service. Please fill my heart with your love, peace, and strength so that I can look after my grandfather's needs in this final act of service. I pray this in Jesus Christ's name."
If you find the task too emotionally taxing, do not hesitate to ask for help from family members or professionals. It is important to take care of your own emotional well-being during this time, and there is no shame in Godly grief or looking after yourself does not mean priority to self. You must also care for yourself to ensure that you maintain your life to stay part of your family to help them in this time of grief. Remember again to lean on the words of Paul in a different circumstance which may be able to give comfort during this difficult time. "We do not want you to be uninformed, brethren, about those who are asleep, so that you will not grieve as do the rest who have no hope. For if we believe that Jesus died and rose again, even so God will bring with Him those who have fallen asleep in Jesus" . This gives further comfort knowing that we will be united in the resurrection.
Lastly if you feel you need to cry, pray for his soul, or take a break, do so. This is a difficult but meaningful task, and it is important to approach it with love, respect, and care. "Bear one another's burdens, and so fulfill the law of Christ" .
Again pray in Jesus Name. It is only through the name of Jesus that believers can call on God and only believing in Jesus Christ can we be saved. After all, it is only through Jesus' payment for our debt of sin from His sacrifice on the cross that we can call on God. Remember that God loves you always and forever, and Jesus Christ has the power to save you. Simply believe in Jesus Christ's sacrifice for your sins, confess your sins, pray to Jesus Christ to be saved, and be baptized in the name of Jesus Christ for the forgiveness of your sins under the new covenant by faith and you shall be saved. After this, Jesus commands us to follow Him.
Know that we are here for you, praying for you and your family in this time of need by the name of and strength in Jesus Christ.