CC Madhya 18.14

kuṇḍera mṛttikā lañā tilaka karila
bhaṭṭācārya-dvārā mṛttikā saṅge kari’ laila
Word for word: 
kuṇḍera — of the lake; mṛttikā — earth; lañā — taking; tilaka karila — formed tilaka; bhaṭṭācārya-dvārā — with the help of Balabhadra Bhaṭṭācārya; mṛttikā — earth; saṅge — along; kari’ — making; laila — took.
Translation: 
Śrī Caitanya Mahāprabhu then marked His body with tilaka made from the mud of Rādhā-kuṇḍa, and with the help of Balabhadra Bhaṭṭācārya, He collected some of the mud and took it with Him.