In our petitions for the sick, it is appropriate to pray, "Thy will be done." Rather than demonstrating unbelief, this can be a sign of implicit trust in God. Reference: E.G. White, "The Upward Look," p. 375.

Full text of the devotional: “Pray, Thy Will Be Done,” December 27

Is any sick among you? let him call for the elders of the church; and let them pray over him, anointing him with oil in the name of the Lord: and the prayer of faith shall save the sick, and the Lord shall raise him up; and if he have committed sins, they shall be forgiven him. James 5:14, 15.

In praying for the sick, it is no sign that we are unbelieving to keep saying, “If it can be for Thy glory, to do this for us, we will praise Thee, and magnify Thy holy name.” ...

As there is no healing power in any human being, we must trust in God, who loves us and who gave Himself for us. Whether we live or die, we are the Lord’s. You have a pitiful, loving, compassionate Redeemer who loves you, who blesses you. He will not leave or forsake you. He who understands the present and future history of all will do that which is for our best good and His name’s glory...

Jesus loves you, and He blesses you. His promise is sure... Christ is the Restorer, Satan is the destroyer. All that mortals can do is to follow implicitly the Word of the Lord. In this they do their part. Will the Lord fail in doing His part? Press your petitions to the throne of grace, and then wait, trustfully, hopefully...

In all my petitions I say, “Not our will, but thine, O Lord, be done.” He knows this [is] not a prayer of doubt, but of perfect trust— that God knows what is best... Our work is to pray, to believe, and to wait patiently for Him who is our Saviour.

I pray, “O God, the living God, reveal Thyself. Make known Thy power unto Thy people, and may this sickness result in our good and Thine own name’s glory.” There is not a thread of unbelief in this prayer, but perfect submission to the will of God, who is mighty to save to the utmost all who believe in Him. Whatever objectionable circumstances attend the case, we have nothing to do with appearances.

God desires us to trust implicitly in Him, and if it is for our good and His name’s glory to do the work, it will be done. We are to wait. The power of the Lord is limitless. We poor mortals need to purify our souls, that when the Lord works for us, it will not ruin us. This is the reason that so few of the sick are healed. If they were [healed], men would be elevated in self-esteem. We must learn from Jesus to be meek and lowly of heart, and we shall find rest unto our souls.

Never for a moment question that God loves you. He does love you, and He does give you evidence of His love. Thank our heavenly Father for a compassionate Saviour, who can save to the uttermost soul and body.—Letter 127, December 27, 1898, to Brother and Sister Wilson.