Ibn Jurayj narrates from Abdullah bin Abi Mulaykah that he said: I sent a message to Sayyiduna Ibn Abbas (may Allah be pleased with them both) to ask about the testimony of children. He replied that Allah Almighty says: 'from among those whom you approve of as witnesses' [Surah al-Baqarah: 282]. These are not among those whom we approve of.
I sent a message to Sayyiduna Ibn al-Zubayr (may Allah be pleased with him) and asked him the same question. He said: "It is likely that if they are asked, they will tell the truth." He said: I have not seen judgment given except according to what Sayyiduna Ibn al-Zubayr (may Allah be pleased with him) said.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20611