Musannaf Ibn Abi Shayba 1:1120

Humaid ibn Abd al-Rahman narrated to us, from Hasan ibn Salih, from Ata ibn al-Sa’ib, from Sa’id ibn Jubayr, from Ibn Abbas, who said: If you are a traveler and you are in a state of major ritual impurity (junub), or you are without ablution (wudu), and you fear that if you perform ablution you will die of thirst, then do not perform ablution with it. Keep it for yourself.