Bhaddiyasutta
Evaṁ me sutaṁ— ekaṁ samayaṁ bhagavā anupiyāyaṁ viharati ambavane. Tena kho pana samayena āyasmā bhaddiyo kāḷīgodhāya putto araññagatopi rukkhamūlagatopi suññāgāragatopi abhikkhaṇaṁ udānaṁ udānesi: “aho sukhaṁ, aho sukhan”ti.
With Bhaddiya
So I have heard. At one time the Buddha was staying near Anupiya in a mango grove. Now at that time, Venerable Bhaddiya son of Kāḷīgodhā, even in the wilderness, at the foot of a tree, or in an empty dwelling, frequently expressed this heartfelt sentiment: “Oh, what bliss! Oh, what bliss!”