The Jātaka of the snake, the frog and the rat

In a previous existence, T’i p’o ta (Devadatta) was once a snake (sarpa). This snake lived in a pool (hrada) in friendship along with a frog (maṇḍūka) and a tortoise (kūrma). In time, the water of the pool dried up completely, but there was nobody the snake could blame for the famine (duṛbhikṣa) and distress; however, he sent the tortoise to call the frog [intending to eat the latter]. But the frog sent the tortoise back with this stanza:

When one becomes poor, one forgets previous dispositions.
One forgets earlier values; eating becomes the main thing.
Remember my words and repeat them to the snake:
The frog will never return to you.

Notes on this Jātaka:

This jātaka occurs in a shorter form in King liu yi siang, T 2121, k. 48, p. 257a (cf. J. Hertel, ZDMG, 1914, p. 67). A more developed form in Mūlasarvāstivādin Vinaya (Ken pen chouo… p’o seng che, T 1450, k. 17, p. 188c–189a, tr. Chavannes, Contes, II, p. 398–400; Dulwa in Schiefner-Ralston, Tibetan Tales, p. 308) which has, not a snake, a frog and a tortoise, but a mongoose, a rat and a snake. These three animals took refuge in the same burrow. A famine breaks out; the rat Gaṅgādatta goes to look for food, in his absence, the mongoose declares that he will eat him if he returns without bringing anything back; the snake Nadasena sends a letter to the rat to warn him of the danger. The rat announces that he will not return because in times of famine, beings listen only to their bellies and lose all feeling of kindness; he does not want to be the victim of the mongoose.