Vaishnava Samhita. Shri Vyasadasa Charitam I. Vol II Book VI Chp 2 Shloka 25

ब्राह्मण उवाच 

अकार्यं कृतवानेवं निर्भयं ब्राह्मणोपि सन्

यज्ञोपवीतं विच्छिन्दन् यतो बध्नासि नूपुरम्  ||

The brahmana asked

Being a brahmana how did you dare do this great sin of cutting off your sacred thread to tie this anklet ?