Al-Adab Al-Mufrad, Book 37, Hadith 884 (English)

'Umar said, "A man is reckoned to be lying when he gives voice to all that he hears." He said, "As for cases of indirect allusion, are they enough to keep a Muslim from lying?"

حَدَّثَنَا الْحَسَنُ بْنُ عُمَرَ، قَالَ‏:‏ حَدَّثَنَا مُعْتَمِرٌ قَالَ أَبِي‏:‏ حَدَّثَنَا ابْنُ عُمَرَ، عَنْ عُمَرَ، فِيمَا أَرَى شَكَّ أَبِي، أَنَّهُ قَالَ‏:‏ حَسْبُ امْرِئٍ مِنَ الْكَذِبِ أَنْ يُحَدِّثَ بِكُلِّ مَا سَمِعَ‏.‏

sunnah.com