Hadith.2961 - Imam (as) said:
"Allah (swt), the Exalted, has not created on the earth a spot more beloved to Him than the Ka'bah, nor more honored by Him. For its sake, Allah (swt), the Exalted, sanctified the four sacred months in His Book 'on the day He created the heavens and the earth' (Surah At-Tawbah 9:36).
Three of these months are consecutive for Hajj, and one is designated specifically for Umrah, which is Rajab."