Aswad bin Qays narrates from his father, from Sayyiduna Umar (may Allah be pleased with him): There are no days in which making up the fasts of Ramadan is more beloved to me than the ten days of Dhu al-Hijjah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8395