He was a Sākiyan and entered the Order when the Buddha visited his kinsmen at Kapilavatthu. For some time he was the Buddha's personal attendant - e.g., when the Buddha breached the Mahāsihanāda Sutta (or the Lomahamsa-pariyāya) (M.i.83 ; MA.i.283; AA.i.163; UdA. 217; J.iv.95).
One day, when entering the city for alms, he saw a nautch girl gaily dressed, dancing to the accompaniment of music and contemplated her as the snare of Māra. Making this his topic of thought, he developed insight into the perishable ness of life and became an arahant (Thag.vs.267 70; ThagA.i.378). Another day (evidently earlier than the previous incident), while walking with the Buddha, they came to a cleft in the road, and the Buddha wished to go along one way, while Nāgasamāla wished to go along another, in spite of the Buddha's warning that it was dangerous. In the end, he put the Buddha's begging bowl and robe on the ground and left him. Brigands waylaid him and ill treated him, breaking his bowl and threatening to kill him. Thereupon he turned back to the Buddha and asked his forgiveness (Ud.viii.7; UdA.425f).
Nāgasamāla was a householder in the time of Padumuttara Buddha, and, seeing the Buddha walking in the sun, he gave him an umbrella. After that, wherever he went a white parasol appeared over his head. For thirty kappas he was king of the gods. He is probably to be identified with Ekachattiya of the Apadana. Ap.ii.405
An arahant. The Apadana (Ap.i.119) distinguishes him from the above, whom it calls Ekachattiya. Thirty one kappas ago he placed a pātali flower on the thupa of Sikhī Buddha. Fifteen kappas ago he was a king named Bhūmiya.
The Apadana Commentary says, however, that this thera was the pacchāsamana (personal attendant) of the Buddha for some time and that he was called Nāgasamāla because his body was tender as nāgabuds.