One verse

Srimad Bhagavatam 11.18.15

11.18.15

बिभृयाच्चेन्मुनिर्वास: कौपीनाच्छादनं परम् । त्यक्तं न दण्डपात्राभ्यामन्यत् किञ्चिदनापदि ॥ १५ ॥

bibhṛyāc cen munir vāsaḥ kaupīnācchādanaṁ param tyaktaṁ na daṇḍa-pātrābhyām anyat kiñcid anāpadi

bibhṛyāt
would wear
cet
if
muniḥ
the sannyāsī
vāsaḥ
clothes
kaupīna
the thick belt and underwear worn by saintly persons
ācchādanam
covering
param
other
tyaktam
given up
na
never
daṇḍa
besides his staff
pātrābhyām
and waterpot
anyat
else
kiñcit
anything
anāpadi
when there is no emergency

If the sannyāsī desires to wear something besides a mere kaupīna, he may use another cloth around his waist and hips to cover the kaupīna. Otherwise, if there is no emergency, he should not accept anything besides his daṇḍa and waterpot.