Śrī Caitanya Caritamrta · Texts Madhya 5.142-143
কপোতেশ্বর দেখিতে গেলা ভক্তগণ সঙ্গে ।
এথা নিত্যানন্দপ্রভু কৈল দণ্ড-ভঙ্গে ॥ ১৪২ ॥
kapoteśvara dekhite gelā bhakta-gaṇa saṅge
ethā nityānanda-prabhu kaila daṇḍa-bhaṅge
When Lord Caitanya Mahāprabhu went to the temple of Lord Śiva known as Kapoteśvara, Nityānanda Prabhu, who was keeping His sannyāsa staff in custody, broke the staff in three parts and threw it into the river Bhārgīnadī. Later this river became known as Daṇḍa-bhāṅgā-nadī.
Read Śrīla Prabhupāda's purport on Vedabase.io