Finishing a good deed is not the same as knowing it was accepted. Ibrahim (AS) and Ismail (AS) asked for acceptance while building the Ka'bah itself. These prayers keep sincerity alive after the work is done.
Rabbana taqabbal minna, innaka anta-s-Sami'u-l-'Alim.
“Our Lord, accept this from us. Indeed, You are the Hearing, the Knowing.”
The prayer Ibrahim (AS) and Ismail (AS) made while raising the foundations of the Ka'bah. Even during a great act of worship, they asked Allah (SWT) to accept it.
Rabbana atina fi-d-dunya hasanah, wa fi-l-akhirati hasanah, wa qina 'adhaba-n-nar.
“Our Lord, give us in this world good and in the Hereafter good, and protect us from the punishment of the Fire.”
A short, complete prayer asking Allah (SWT) for every kind of genuine good in this life, lasting good in the Hereafter, and protection from the Fire.
Rabbana atmim lana nurana wa-ghfir lana, innaka 'ala kulli shay'in qadir.
“Our Lord, perfect for us our light and forgive us. Indeed, You are over all things competent.”
A prayer for complete light and forgiveness on the Day believers will need both. It asks Allah (SWT) to carry faith to its good completion, not merely to give a promising beginning.
Rabbi inni nadhartu laka ma fi batni muharraran fa-taqabbal minni, innaka anta-s-Sami'u-l-'Alim.
“My Lord, I have pledged to You what is in my womb, dedicated to Your service, so accept this from me. Indeed, You are the Hearing, the Knowing.”
The wife of 'Imran dedicated the child she was carrying to Allah's service while she was still pregnant.
Rabbana amanna bima anzalta wa-ttaba'na-r-rasula fa-ktubna ma'a-sh-shahidin.
“Our Lord, we have believed in what You revealed and have followed the messenger, so register us among the witnesses.”
The disciples of 'Isa (AS) declared themselves helpers of Allah (SWT) and then prayed this.
Rabbi hab li hukman wa alhiqni bi-s-salihin, wa-j'al li lisana sidqin fi-l-akhirin, wa-j'alni min warathati jannati-n-na'im.
“My Lord, grant me authority and join me with the righteous. Grant me an honourable mention among later generations, and make me one of the inheritors of the Garden of Bliss.”
Ibrahim (AS) prayed this after declaring to his father and his people that he worshipped only the Lord of the worlds.
Rabbi awzi'ni an ashkura ni'mataka-llati an'amta 'alayya wa 'ala walidayya wa an a'mala salihan tardahu wa adkhilni bi-rahmatika fi 'ibadika-s-salihin.
“My Lord, enable me to be grateful for Your favour which You have bestowed upon me and upon my parents, and to do righteous deeds that please You. And admit me by Your mercy among Your righteous servants.”
Sulayman (AS) said this, smiling, after he understood the words of an ant warning the other ants about his army.