Dhikr after salam — seeking forgiveness
أَسْـتَغْفِرُ الله (ثلاثاً) اللّهُـمَّ أَنْـتَ السَّلامُ،...
أَسْـتَغْفِرُ الله (ثلاثاً) اللّهُـمَّ أَنْـتَ السَّلامُ، وَمِـنْكَ السَّلام، تَبارَكْتَ يا ذا الجَـلالِ وَالإِكْـرام
Astaghfirul-lah (three times). Allahumma antas-salam waminkas-salam, tabarakta ya thal-jalali wal-ikram
Translation
I ask Allah for forgiveness (three times). O Allah, You are As-Salam and from You is all peace, blessed are You, O Possessor of majesty and honour.
When to recite
Recited immediately after giving salam at the end of prayer.
Source / Reference
Muslim 1/414