From Sahih Bukhari (Hadith 3993):
Narrated Mu`adh bin Rifa`a bin Rafi`:Rifa`a was one of the warriors of Badr while (his father) Rafi` was one of the people of Al-`Aqaba (i.e. those who gave the pledge of allegiance at Al-`Aqaba). Rafi` used to say to his son, "I would not have been happier if I had taken part in the Badr battle instead of taking part in the 'Aqaba pledge
Reference: Bukhari 3993