While we were with the Messenger of Allah! ﷺ a man of Banu Salmah came to Him and said: Messenger of Allah is there any kindness left that I can do to my parents after their death? He replied: Yes, you can invoke blessings on them, forgiveness for them, carry out their final instructions after their death, join ties of relationship which are dependent on them, and honour their friends. (Using translation from Abū Dāʾūd 5142)
أَنَّهُ سَمِعَ أَبَا أُسَيْدٍ مَالِكَ بْنَ رَبِيعَةَ السَّاعِدِيَّ يَقُولُ بَيْنَمَا نَحْنُ عِنْدَ رَسُولِ اللَّهِ ﷺ إِذْ جَاءَهُ رَجُلٌ مِنْ بَنِي سَلَمَةَ فَقَالَ يَا رَسُولَ اللَّهِ هَلْ بَقِيَ مِنْ بِرِّ أَبَوَيَّ شَيْءٌ أَبَرُّهُمَا بِهِ مِنْ بَعْدِ مَوْتِهِمَا؟ قَالَ «نَعَمُ الصَّلَاةُ عَلَيْهِمَا وَالِاسْتِغْفَارُ لَهُمَا وَإِنْفَاذُ عُهُودِهِمَا وَإِكْرَامُ صَدِيقِهِمَا وَصِلَةُ الرَّحِمِ الَّذِي لَا رَحِمَ لَكَ إِلَّا مِنْ قِبَلِهِمَا»