Hadith
Addressing Imam Ali (a.s), the Holy Prophet (saw) says:
 يا عليّ ، تارك الحجّ وهو مستطيع  كافر ، يقول الله تبارك وتعالى : (وَلِلّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إلَيْهِ سَبِيلاً وَمَنْ كَفَرَ فَإِنَّ اللهَ غَنِيٌّ عَنِ الْعَالَمِينَ) .يا عليّ ، مَن سوّف الحجّ حتّى يموت ، بعثه الله يوم القيامة يهوديّاً أو نصرانيّاً.
O Ali, one who forsakes Hajj while having the means (to perform it) is unbeliever, for Allah Himself has said: 'And pilgrimage to the House (Hajj) is incumbent upon men for the sake of Allah, upon everyone who is able to undertake the journey to it; and whoever disbelieves then surely Allah is Self-Sufficient above any need of the worlds.' O Ali, anyone who delays Hajj until he dies, Allah will raise him as Jew or Christian on the Day of Judgment.See Men la Yahzuruh ul-Faqih; chapter: Miscellaneous matters