Arabic (Original)
قَالَ وَكَانَ يَقُولُ دَعْ مَا يَرِيبُكَ إِلَى مَا لَا يَرِيبُكَ فَإِنَّ الصِّدْقَ طُمَأْنِينَةٌ وَإِنَّ الْكَذِبَ رِيبَةٌ.
English Translation
He (the Prophet, peace be upon him) used to say: 'Leave what makes you doubt for what does not make you doubt, for truthfulness is tranquility and lying is doubt.'