References – AN 6.48: Apparent in the Present Life (2nd) 
“How did the Buddha deal with this issue of people becoming enlightened contemporaneous with him and getting a little bit crazy? His contemporaries also had siddhis [psychic powers] and practices? How did he distinguish between Buddhist and non-Buddhist attainments?” Answered by Ajahn Pasanno and Ajahn Amaro. [Buddha/Biography] [Liberation] [Delusion] [Psychic powers] // [Cessation of Suffering] [Self-identity view] [Relinquishment] [Becoming]
Sutta: AN 6.48: A proper declaration of full knowledge does not include a sense of me and mine.
Vinaya: Mahāvagga 1.38: Rules for wanderers of other sects wanting to become bhikkhus.