This warning did not just come from ibn Sireen and Ayoob only. This came from Allaah, His Messenger, the Sahaabah, and those that follow the Imaams of Islaam. The weak ones should not expose themselves to trials and he should distance himself from the people of bid'.
Subhanak Allaahuma wa bihamdika ash-hadu anlaa illaaha illa anta astaghfiruka wa atubu ilayk
If I said anything correct, then it is from Allaah (subhanahu wa taa'ala), and if I erred, then that is from me and shaytan.