Is it permissible for me to intend, with a supererogatory prayer, to draw closer to God, relieve worries, be protected from tribulations, and attain mercy in both abodes when helping my parents?

Prayer is one of the greatest means by which worries are repelled. That is why the Prophet (peace be upon him) would resort to it whenever he was distressed, in fulfillment of the Almighty's saying: "And seek help through patience and prayer." It is also a reason for protecting the servant from trials.

Assisting one's parents and showing kindness to them are among the reasons for attaining Allah's mercy, as the Almighty says: "Indeed, the mercy of Allah is near to the doers of good."

There is no harm in praying and honoring one's parents with the intentions mentioned, and this does not contradict sincerity to Allah Almighty. Seeking Allah's reward and the recompense promised for acts of worship is legitimate, as the Almighty said: "Those whom they invoke seek means of access to their Lord, [striving as to] which of them would be nearest, and they hope for His mercy and fear His punishment. Indeed, the punishment of your Lord is ever to be feared."