Ācārāṅga Sūtra 2.6.2

A monk or a nun, entering the abode of a householder for the sake of alms, should after examining their alms-bowl, taking out any living beings, and wiping off the dust, circumspectly enter or leave the householder's abode. The Kevalin says: This is the reason: Living beings, seeds or dust might fall into his bowl. Hence it has been said to the mendicant, &c., that he should after examining his alms-bowl, taking out any living beings, circumspectly enter or leave the householder's abode.

On such an occasion the householder might perhaps, going in the house, fill the alms-bowl with cold water and, returning, offer it him; (the mendicant) should not accept such an alms-bowl' either in the householder's hand or his vessel; for it is impure and unacceptable.

Perhaps he has, inadvertently, accepted it; then he should empty it again in (the householder's) water-pot; or (on his objecting to it) he should put down the bowl and the water somewhere, or empty it in some wet place.

A monk or a nun should not wipe or rub a wet or moist alms-bowl. But when they perceive that on their alms-bowl the water has dried up and the moisture is gone, then they may circumspectly wipe or rub it.

A monk or a nun wanting to enter the abode of a householder, should enter or leave it, for the sake of alms, with their bowl; also on going to the out-of-door place for religious practices or study; or on wandering from village to village. If a strong and widely spread rain pours down, they should take the same care of their alms-bowl as is prescribed for clothes (in the preceding Lecture, Lesson, § 1). This is the whole duty, &c. Thus I say.