In the Chinese translation of an Udānavarga commentary (出曜経, Taishō no. 212, 399 CE), an interesting verse is quoted as “Long ago bhadanta Aśvaghoṣa 馬聲 has preached this.” The same verse is quoted without credit in the *Mahāprajñāpāramitopadeśa 大智度論 (Taishō no. 1509), translated by Kumārajīva, and the same verse appears once again in prose in Kumārajīva’s translation of the Buddhist Yoga Manual (坐禅三昧経, Taishō no. 614). Is this really a verse of Aśvaghoṣa, and if so, to which work of Aśvaghoṣa is it to be attributed? In this article I present the original Sanskrit text of this verse in Śārdūlavikrīḍita metre, which I have obtained through my ongoing research on the decipherment of the Sanskrit manuscript of the Tridaṇḍamālā attributed to Aśvaghoṣa, I have analysed why the three Chinese translations cite this verse, and I clarify which of Aśvaghoṣa’s works this verse belongs to.