It is narrated from Imam Tawus (may Allah have mercy on him) that he said: "I have not seen anyone more knowledgeable than Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both), nor have I found anyone greater in piety, scrupulousness and avoidance of doubtful matters than Sayyiduna Abdullah bin Umar (may Allah be pleased with them both)."
The chain of this athar (report) is sahih (authentic); Imam Ahmad bin Mani' recorded it in his Musnad, and all its narrators are thiqat (trustworthy) and reliable.
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب المناقب / 4071
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :إسناده ضعيف » «انفرد به المصنف من هذا الطريق»