Narrated Buraidah (RA) in another version of the above Hadith regarding 'Asr (afternoon prayer):

"When the sun is white and clear." [Reported by Muslim].

وَلَهُ مِنْ حَدِيثِ بُرَيْدَةَ فِي اَلْعَصْرِ: { وَالشَّمْسُ بَيْضَاءُ نَقِيَّةٌ } [1]‏ .‏