After completing the wajib shalat, Nabi would say 'Astaghfirullah' three times, then say: 'Allahumma Antas-Salam wa minkas-Salam, tabarakta ya Dhal-Jalali wal-Ikram.' This combines seeking forgiveness with praising Allah's majesty immediately after worship.
أَسْتَغْفِرُ اللَّهَ، أَسْتَغْفِرُ اللَّهَ، أَسْتَغْفِرُ اللَّهَ. اللَّهُمَّ أَنْتَ السَّلَامُ وَمِنْكَ السَّلَامُ، تَبَارَكْتَ يَا ذَا الْجَلَالِ وَالْإِكْرَامِ
Astaghfirullah, Astaghfirullah, Astaghfirullah. Allahumma Antas-Salam wa minkas-Salam, tabarakta ya Dhal-Jalali wal-Ikram.
Meaning: I seek forgiveness from Allah. I seek forgiveness from Allah. I seek forgiveness from Allah. O Allah, You are Peace and from You is peace. Blessed are You, O Possessor of Majesty and Honor.
Source: Sahih Muslim #591Seeking forgiveness immediately after shalat reflects humility before Allah, acknowledging that even our worship may contain imperfections. Nabi consistently practiced this, teaching that we should never feel self-satisfied with our worship but always turn to Allah for forgiveness and mercy.
أَسْتَغْفِرُ اللَّهَ، أَسْتَغْفِرُ اللَّهَ، أَسْتَغْفِرُ اللَّهَ. اللَّهُمَّ أَنْتَ السَّلَامُ وَمِنْكَ السَّلَامُ، تَبَارَكْتَ يَا ذَا الْجَلَالِ وَالْإِكْرَامِ
The Messenger of Allah (peace be upon him), when he finished his prayer, would seek forgiveness three times and say: 'Allahumma Antas-Salam wa minkas-Salam, tabarakta ya Dhal-Jalali wal-Ikram.'