Ali bin Zayd narrates that when Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) buried Sayyiduna Zayd bin Thabit (may Allah be pleased with him) and threw earth on his grave, he said: This is how knowledge is buried. I related this to Ali bin al-Husayn (may Allah have mercy on him), and he said: As for Sayyiduna Ibn Abbas (may Allah be pleased with them both), by Allah, he was remarkable; by Allah! A great deal of knowledge was buried with him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6734