Laṅkāvatāra Sūtra
The "sutta" is quoted in the Laṅkāvatāra Sūtra (Section LXII; p. 145). It is also cited in Sanskrit in Nāgārjuna's Mūlamadhyamakakārika (MMK 15.7) and in commentaries on this work by Candrakīrti, namely "Prassanapadā" and "Madhyamakāvatārabhāṣya".