The Prophet (peace and blessings be upon him) said:
"The greatest of days in the sight of Allah Almighty is the Day of Sacrifice (Yawm al-Nahr, that is, 10 Dhul-Hijjah), and after it the Day of Settling (Yawm al-Qarr, 11 Dhul-Hijjah, the day of staying in Mina)."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 1064
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[حم د ك] عن عبد الله بن قرط. المشكاة ٢٦٤٣. إرواء ٢٠١٨: حب.