The timing of the permission for the kaṭhina robe

The Pali Vinaya records that thirty monks from Pāvā, on their way to see the Buddha at Sāvatthī, could not arrive before the rains retreat began and had to keep the retreat at Sāketa (a city of ancient India); when it ended they came on through rain and mud. The Buddha therefore allowed monastics to accept the kaṭhina robe after the rains retreat and relaxed five restrictions of the rules. A sub-commentary on the Vinaya of the Southern tradition says this permission was given in the Buddha's later years, in the reign of Ajātasattu. Source text