Narrated A man: Ghalib said: When we were sitting at al-Hasan's door, a man came along. He said: My father told me on the authority of my grandfather, saying: My father sent me to the Messenger of Allah (ﷺ) and said: Go to him and give him a greeting. So I went to him and said: My father sends you a greeting. He said: Upon you and upon your father be peace.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا إِسْمَاعِيلُ، عَنْ غَالِبٍ، قَالَ إِنَّا لَجُلُوسٌ بِبَابِ الْحَسَنِ إِذْ جَاءَ رَجُلٌ فَقَالَ حَدَّثَنِي أَبِي عَنْ جَدِّي قَالَ بَعَثَنِي أَبِي إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ ائْتِهِ فَأَقْرِئْهُ السَّلاَمَ . قَالَ فَأَتَيْتُهُ فَقُلْتُ إِنَّ أَبِي يُقْرِئُكَ السَّلاَمَ . فَقَالَ " عَلَيْكَ وَعَلَى أَبِيكَ السَّلاَمُ " .
sunnah.com