حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، وَعَلِيُّ بْنُ مُحَمَّدٍ، قَالاَ حَدَّثَنَا مَنْصُورُ بْنُ وَرْدَانَ، حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ الأَعْلَى، عَنْ أَبِيهِ، عَنْ أَبِي الْبَخْتَرِيِّ، عَنْ عَلِيٍّ، قَالَ لَمَّا نَزَلَتْ ‏{‏وَلِلَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إِلَيْهِ سَبِيلاً‏}‏‏.‏ قَالُوا يَا رَسُولَ اللَّهِ الْحَجُّ فِي كُلِّ عَامٍ فَسَكَتَ ثُمَّ قَالُوا أَفِي كُلِّ عَامٍ فَقَالَ ‏"‏ لاَ وَلَوْ قُلْتُ نَعَمْ لَوَجَبَتْ ‏"‏ ‏.‏ فَنَزَلَتْ ‏{‏يَا أَيُّهَا الَّذِينَ آمَنُوا لاَ تَسْأَلُوا عَنْ أَشْيَاءَ إِنْ تُبْدَ لَكُمْ تَسُؤْكُمْ ‏}‏‏.‏

It wasnarrated that ‘Ali said: “When the following was revealed:“AndHajj (pilgrimage to Makkah) to the House (Ka’bah) is a duty thatmankind owes to Allah, for whoever can bear the way.” [3:97] Theyasked: ‘O Messenger of Allah, is Hajj every year?’ He remainedsilent.They asked: ‘Is it every year?’ He said: ‘No. If I hadsaid yes, itwould have become obligatory.’ Then the following wasrevealed: “O youwho believe! Ask not about things which, if madeplain to you, maycause you trouble.’” [5:101] Translation Not Available

Book Ref: Sunan Ibn Majah Book 25 Hadith 2884
Web Ref:  Sunan Ibn Majah Vol 4 Book 25 Hadith 2884