Bhagavatam 0381: Difference between manas and buddhi
Puruśottamāya namah Hiraṇyakaśipu continued, “When the manas (the processing mind) wavers due to the influence of these material objects which are the outcomes of trigunas, then the Self which in reality is unmoving and beyond transformations, attains oneness with the manas and believes it has transformed along with it.