Amīr al-mu’minīn’s warning to Anas ibn Mālik

311. When Amīr al-mu’minīn, peace be upon him, came to Baṣrah he sent Anas ibn Mālik to Ṭalḥah and az-Zubayr to make them recall what he (Anas) himself had heard the Messenger of Allāh, peace be upon him and his…

Thereupon, Amīr al-mu’minīn, peace be upon him, said: If you are speaking a lie Allāh may afflict you with white spots (leucoderma) which even the turban may not cover.

as-Sayyid ar-Raḍī says: White spot means leucoderma. After sometime this disease did occur to Anas’s face so much so that he was never seen without a veil. [1]