Chiggaḷayuga Sutta
1. Paṭhama Chiggaḷayuga Sutta.– It is more probable that a blind turtle, rising to the surface only once in a hundred years, should put his neck through a yoke (chiggala) with a single hole, floating about in the ocean, than that a fool who has gone to the Downfall should become a man again (S.v.455; cp. M.iii.169; Thig.500).
2. Dutiya Chiggaḷayuga Sutta.– Similar to 2. It is more probable that a turtle, etc., ... than that one should get birth in a human form, or that a Tathāgata should arise in the world, or that the Dhamma and Vinaya proclaimed by a Tathāgata should be shown in the world. See also the Vāla Sutta (v.l. Tāḷacchiggaḷa Sutta, S.v.456).
Chiggala Sutta.– See Vāla Sutta. S.v.453.