The Prophet ﷺ did Istighfār three times after every Ṣalāh and asked for peace
MUSLIM 591:
from Thawbān —
Whenever the Messenger of Allah ﷺ finished his prayer, he sought forgiveness three times and said: "O Allah! You are Salām (Peace), and peace comes from Your; Blessed are You, O Possessor of Majesty and Honor."
al-Walīd said that I said to Awzāʿī, "How ˹should be˺ the seeking of forgiveness?" He replied, "You should say: astaghfiru Allāh, astaghfiru Allāh (I seek forgiveness from Allah, I seek forgiveness from Allah.)"
مسلم ٥٩١:
عن ثوبان —
كَانَ رَسُولُ اللَّهِ ﷺ إِذَا انْصَرَفَ مِنْ صَلاَتِهِ اسْتَغْفَرَ ثَلاَثًا وَقَالَ: (اللَّهُمَّ أَنْتَ السَّلاَمُ وَمِنْكَ السَّلاَمُ، تَبَارَكْتَ ذَا الْجَلاَلِ وَالإِكْرَامِ۔)
قَالَ الْوَلِيدُ: فَقُلْتُ لِلأَوْزَاعِيِّ: كَيْفَ الاِسْتِغْفَارُ؟ قَالَ تَقُولُ: (أَسْتَغْفِرُ اللَّهَ أَسْتَغْفِرُ اللَّهَ)۔