Riyad as-SalihinChapter 8Hadith 585
Full Sharh — Riyad as-Salihin 585
وعن ابن عباس، رضي الله عنهما، قال: كان رسول الله صلى الله عليه وسلم "لا يفطر أيام البيض في حضر ولا سفر" ((رواه النسائي بإسناد حسن)).
English Translation
Ibn 'Abbas (May Allah be pleased with them) reported:: It was the practice of the Messenger of Allah (ﷺ) to not to omit fast on 'bright days' whether he was staying at a place or on a journey..
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Virtues
Hadith Number
585