Srimad Bhagavatam Canto 11, Chapter 18, Text 15

SB 11.18.15

bibhryac cen munir vasah
 kaupinacchadanam param
tyaktam na danda-patrabhyam
 anyat kiñcid anapadi
 
Translation: 
 
If the sannyasi desires to wear something besides a mere kaupina, he may use another cloth around his waist and hips to cover the kaupina. Otherwise, if there is no emergency, he should not accept anything besides his danda and waterpot.
 
Purport: 
 
A sannyasi attracted to material possessions will spoil his worship of Lord Krsna.
Srimad Bhagavatam Canto 11, Chapter 18, Text 14
Srimad Bhagavatam Canto 11, Chapter 18, Text 16