Gemara:

Shevuot 

Collections: Rabbi Meth Mini Chabura

References: Shevuot: 14a ,  Shevuot: 14b  

Description

Knowing that something may be assur is akin to knowing that something is certainly assur in that both safek issur and vadai issur are practically forbidden. However, safek issur provides less guard against the yetzer hara. Also, the issur deoraisa of partaking of safek issur may fall under the same heading as the issur vadai, but may fall under an independent general heading of safek issur.