A rich brahmin of Campā, very learned in the Vedas; he lived in a royal domain, given to him as royal fief by King Bimbisāra. When the Buddha was in Campā, on the banks of the Gaggarā-lake, Sonadanda visited him in spite of the protests of his friends and colleagues. Their conversation is recorded in the Sonadanda Sutta. At the end of the discourse, Sonadanda expressed his appreciation of the Buddha and his doctrine, and invited him and his monks to a meal. At the conclusion of the meal Sonadanda asked the Buddha to forgive him if, in the presence of the brahmins, he did not make humble obeisance to the Buddha, but merely saluted him.
Buddhaghosa explains (D.i.111ff., DA.i.292ff) that this was because Sonadanda was much older than the Buddha and did not wish people to see him paying homage to one young enough to be his grandson. But, probably, Sonadanda's conversion to the faith was only partial.
Angaka was Sonadanda's sister's son.