Muwatta Malik, Book 48, Hadith 2 (USC-MSA)

Yahya related to me from Malik that he heard that Umar ibn al- Khattab said, "I love to look at a Qur'an reader in white garments."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ إِنِّي لأُحِبُّ أَنْ أَنْظُرَ، إِلَى الْقَارِئِ أَبْيَضَ الثِّيَابِ ‏.‏

sunnah.com

also referenced under: Book 48, Hadith 1655 (In-Book)