Vaishnava Samhita. Ghanananda Charitam. Vol III Book VI Chp 21 Shlokas 1 - 6

श्रीसद्गुरुरुवाच 
तपोधना ब्राह्मणाश्च क्षत्रियाश्च यशोधनाः |
वैष्णवानां विरक्तानां श्रीवनस्य रजो धनम् ||
नृत्यन्तीनां मुकुन्देन गोलोके रासमण्डले |
गोपिकानां चन्दनेन सञ्जाता श्वेतमृत्तिका ||
तयैव वैष्णवो नित्यमूर्ध्वपुण्ड्रं वहेच्हुभम् |
केशवादीनि नामानि द्वादशाङ्गेषु कीर्तयन् ||
गोपीचन्दनमित्येतच्छ्रीवनस्य रजः स्मृतम् |
यस्त धारणमात्रेण प्रीणाति भगवान् हरिः ||
ब्रह्मादयोपि वाञ्छन्ति श्रीवनस्य रजःसदा |
यद्गोविन्दपदाम्भोजदिव्यसौरभरम्युतम् ||
उद्धवप्रमुखाभक्तास्तृणीकृतजगत्त्रयाः |
बृन्दावनरजो नित्यं वहन्ति शिरसा शुभम्  ||

Shri Sadguru said

Tapas is the asset of the brahmanas. Fame is the asset of the Kshatriyas. The sacred dust of Shri Brindavan is the wealth of the determined vaishnavas. The sacred clay (Tiruman used for tilak by the vaishnavas) took birth in the sandal paste used by the Gopis who engaged in the Raasa dance with Shri Krishna in the Goloka. Daily a vaishnava should apply that Tiruman or sacred clay on twelve different parts of his body (in the form of Oordhvapundram) uttering the Divine Names of the Lord, like Keshava. This Gopi chandan (sandal paste) is only the sacred dust of Shri Brindavan. When it is applied Bhagavan Shri Krishna gets pleased. The sacred dust of Shri Brindavan which smells the sweet fragrance of the divine feet of Shri Govinda, is loved even by all the devas like Brahma. Even bhaktas like Uddhava who attach least importance to the entire world and consider it as insignificant as a blade of grass, like to bear this sacred dust of Shri Brindavan on their heads.