Adbhutasagara 48.58

48.58

devalastūdake'hani śakradhanuṣo drarśanaṃ dvimāsikaṃ riṣṭamāha|
jale cendradhanurvā'pi yadi paśyennaro'hani|
māsadvayena mriyate nāsti tatra vicāraṇā||

Devala, however, states that seeing a rainbow in water by day is a two-month sign of death:
"If a man should see a rainbow in water even by day,
he dies in two months; of that there is no doubt."