PTS cs 9 ‘Venerable Nāgasena, those three qualities of the deer you say he ought to take, which are they?’
‘Just, O king, as the deer frequents the forest by day, and spends the night in the open air; just so, O king, should the strenuous Bhikshu, earnest in effort, pass the day in the forest, and the night under the open sky. This, O king, is the first quality of the deer he ought to have. PTS vp Pali 396 For it was said, O king, by the Blessed One, the god over all gods, in the exposition called the Lomahaṁsana Pariyāya:
“And I, Sāriputta, when the nights are cold and wintry, at the time of the eights (the Ashṭakā festivals), when the snow is falling, at such times did I pass the night under the open sky, and the day in the woods. And in the last month of the hot season I spent the day under the open sky, and the night in the woods.” PTS vp En 332
PTS cs 10 ‘And again, O king, as the deer, when a javelin or an arrow is falling upon him, dodges it and escapes, not allowing his body to remain in its way; just so, O king, should the strenuous Bhikshu, earnest in effort, when evil inclinations fall upon him, dodge them, and escape, placing not his mind in their way. This, O king, is the second quality of the deer he ought to have.
PTS cs 11 ‘And again, O king, as the deer on catching sight of men escapes this way or that, that they may not see him; just so, O king, should the strenuous Bhikshu, earnest in effort, when he sees men of quarrelsome habits, given to contentions and strife and disputes, wicked men and inert, fond of society—then should he escape hither or thither that neither should they see him, nor he them. This, O king, is the third quality of the deer he ought to have. For it was said, O king, by Sāriputta, the Elder, the Commander of the Faith:
“Let not the man with evil in his heart,
Inert, bereft of zeal, of wicked life,
Knowing but little of the sacred words—
Let not that man, at any time or place,
Be my companion, or associate with me.”