There are some Suttas are not really the words of Buddha. For example, Karajakaya Sutta (AN 10.219), although this is the sutta of four nikayas but this sutta seems to have been influenced by Jains. It’s believed there was error during transmission therefore this sutta was patched from different sources.
From wikipedia about Anguttara Nikaya
According to Keown, “there is considerable disparity between the Pāli and the Sarvāstivādin versions, with more than two-thirds of the sūtras found in one but not the other compilation, which suggests that much of this portion of the Sūtra Piṭaka was not formed until a fairly late date.”
What about Sanghabheda Sutta, what is considered schism in the Sangha, is this truly the words of Buddha or is this something developed later? Thanks.