Mustadrak al-Hakim — Hadith 1955

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that whenever he sat in any gathering, whether anyone else was there or not, he would always make this supplication: 'Allahummaghfir li ma qaddamtu wa ma akhkhart, wa ma asrartu wa ma a'lant, wa ma anta a'lamu bihi minni. Allahummarzuqni min ta'atika ma tahulu bayni wa bayna ma'siyatik, warzuqni min khashyatika ma tuballighuni bihi rahmatak, warzuqni minal-yaqini ma tuhawwinu bihi 'alayya masa'ibad-dunya, wa barik li fi sam'i wa basari, waj'alhumal-waritha minni. Allahummaj'al tha'ri mimman zalamani, wansurni 'ala man 'adani, wa la taj'alid-dunya akbara hammi, wa la mablagha 'ilmi. Allahumma wa la tusallit 'alayya man la yarhamuni' (O Allah, forgive me the sins I committed before and those I committed after, those I committed in secret and those I committed openly, and those that You know better than I do. O Allah, grant me such obedience to You as will stand between me and disobedience to You, grant me such fear of You as will bring me to Your mercy, and grant me such certainty by which You make the calamities of this world easy for me. Bless my hearing and my sight and make them my heir. O Allah, take my retribution from the one who wronged me, help me against the one who showed enmity to me, and do not make this world my greatest concern or the limit of my knowledge. O Allah, do not give power over me to one who will not show me mercy). Ibn Umar (may Allah be pleased with them both) was asked about these words, and he said that the Messenger of Allah (peace and blessings be upon him) used to conclude his gatherings with these very words.
This hadith is sahih (authentic) on the condition of Imam Bukhari, but the two Shaykhs (Bukhari and Muslim) did not record it.