Son of one of Suddhodana's ministers at Kapilavatthu; he was born on the same day as the Buddha and grew up as his playfellow. After Gotama left the world, Suddhodana made Kāludāyī one of his most trusted counsellors. When the king heard of his son's Enlightenment he sent several of his ministers with large retinues to bring the Buddha to Kapilavatthu, but they all became arahants as soon as they heard the Buddha's preaching and then forgot their mission. In the end the king sent Kāludāyī, on the understanding that he should first be allowed to join the Order. (According to Mtu.iii.233, he was accompanied by Channa in this mission). He went to the Buddha and, having listened to him, himself became an arahant. When the rains fell, covering the earth with the glory of leaves and flowers, Kāludāyī felt that it was time for the Buddha to visit his kinsmen, and gave him their invitation, singing the season's beauties in a series of verses. The Buddha took sixty days in covering the sixty leagues from Rājagaha to Kapilavatthu, and each day Kāludāyī went by air to the king's palace to tell him of the progress made in the journey and to bring back to the Buddha from the palace a bowl full of excellent food. By the time the Buddha reached his home his kinsmen were already full of faith in him. Because Kāludāyī accomplished this feat, he was declared pre-eminent among those who gladdened the clans (kulappasādakānam aggo) (A.i.25; Thag.527-36; J.i.54, 86f; AA.i.107, 117; ThagA.i.497ff; UdA.168; DA.ii.425).
It is said that he was called Udāyī because he was born on a day on which the citizens were full of joy (udaggacittadivase jātattā); and called Kāla because of his slightly dark colour. AA.i.167; ThagA.i.498.
According to the Apadāna (ii.500f; see also Ap.i.86f, where another set of verses is attributed to Kāludāyī), Kāludāyī had been the son of a minister of Hamsavatī during the time of Padumuttara Buddha, and having heard the Buddha utter the praises of a monk skilled in converting families, had wished for the same eminence.
The Anguttara Nikāya (A.iv.449f) records a conversation between Udāyī (who, according to Buddhaghosa (AA.ii.815), is to be identified with Kāludāyī) and Ananda. Udāyī asks Ananda to explain in detail a question which is recorded in the Samyutta Nikāya (S.i.48) as having been asked of the Buddha by Pañcālacanda-devaputta (see Pañcāla Sutta).
The Dhammapada Commentary (iv.143) refers to an assembly at which Kāludāyī was present, his body of golden hue, sitting near Pasenadi, at sunset, with the moon rising in the eastern sky. Ananda looks at them and declares how the Buddha suffuses them all with his glory.
Kāludāyī is identified with Sakka in the Bhisa Jātaka (J.iv.314).