Once, while he was at Silāvati musing on his good fortune as a monk, Māra tried to terrify him. Samiddhi told the Buddha of this, but the Buddha asked him to stay on where he was. He obeyed, and soon afterwards won arahantship. He then declared his attainment in a verse and Māra retired discomfited. SN.i.119f. Thag.46
Once when Samiddhi was drying himself after bathing in the Tapodā, a Deva approached and questioned him on the Bhaddekaratta Sutta. Samiddhi confessed ignorance, and the Deva asked him to learn it from the Buddha. This he did from a brief sermon preached to him by the Buddha, which Mahā Kaccāna later enlarged into the Mahā Kaccāna-Bhaddekaratta Sutta. MN.iii.192f. A conversation between Potaliputta and Samiddhi, three years after the latter had joined the Order, led to the preaching of the Mahākammavibhaṅga Sutta. MN.iii.207 In the sutta the Buddha speaks of Samiddhi as a foolish man, and Samiddhi is also teased by Potaliputta for pretending to expound the Dhamma after being only three years in the Order. The Aṅguttara AN.iv.385f. contains a record of a lesson given by Sāriputta to Samiddhi regarding thoghts and intentions.