Ācārāṅga Sūtra 0.7.7

To a naked monk the thought occurs: I can bear the pricking of grass, the influence of cold and heat, the stinging of flies and mosquitos; these and other various painful feelings I can sustain, but I cannot leave off the covering of the privities. Then he may cover his privities with a piece of cloth. A naked monk who perseveres in this conduct, sustains repeatedly these and other various painful feelings the grass pricks him, heat and cold attack him, flies and mosquitos sting him. A naked monk (should be) aspiring to freedom from bonds. Penance suits him. Knowing what the Revered One has declared, one should thoroughly and in all respects conform to it.

A monk who has come to any of the following resolutions, having collected food, &c., I shall give of it to other monks, and I shall eat (what they have) brought; (or) having collected food, &c., I shall give of it to other monks, but I shall not eat (what they have) brought; (or) having collected food, &c., I shall not give of it to other monks, but I shall eat (what they have) brought; (or) having collected food, &c., I shall not give of it to other monks, nor eat (what they have) brought;

(or) I shall assist a fellow-ascetic with the remnants of my dinner, which is acceptable' and remained in the same state in which it was received, and I shall accept the assistance of fellow-ascetics as regards the remnants of their dinner, which is acceptable and remained in the same state in which it was received;-(that monk should keep these vows even if he should run the risk of his life)

-aspiring to freedom from bonds. Penance suits him. Knowing what the Revered One has declared, one should thoroughly conform to it.

(The last two paragraphs of the last lesson are to be reproduced here.) Thus I say.