"When Allah revealed: And Hajj to the House is a duty that mankind owes to Allah, for whomever is able to bear the journey. They said: 'O Messenger of Allah! Is that every year?' He remained silent. So they said: 'O Messenger of Allah! Is that every year?' He said: 'No. If I had said yes, then it would have been made obligatory.' So Allah revealed: O you who believe! Do not ask about things which, if made plain to you, may cause you trouble.  

لَمَّا نَزَلَتْ ( وَلِلَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إِلَيْهِ سَبِيلاً ) قَالُوا يَا رَسُولَ اللَّهِ أَفِي كُلِّ عَامٍ فَسَكَتَ فَقَالُوا يَا رَسُولَ اللَّهِ أَفِي كُلِّ عَامٍ قَالَ لاَ وَلَوْ قُلْتُ نَعَمْ لَوَجَبَتْ فَأَنْزَلَ اللَّهُ (يَا أَيُّهَا الَّذِينَ آمَنُوا لاَ تَسْأَلُوا عَنْ أَشْيَاءَ إِنْ تُبْدَ لَكُمْ تَسُؤْكُمْ ) قَالَ وَفِي الْبَابِ عَنِ ابْنِ عَبَّاسٍ وَأَبِي هُرَيْرَةَ  

from 'Ali who said: "When (the following) was revealed: And Hajj to the House is a duty that mankind owes to Allah, for those who are able to undertake the journey (3:97). They said: 'O Messenger of Allah! Every year?' But he was silent. So they said: 'O Messenger of Allah! Every year?' He said: 'No. If I were to say yes, then it would be required.' And Allah, Mighty and Sublime is He, revealed O you who believe! Ask not about things which, if made plain to you, may cause you trouble (5:101)."  

لَمَّا نَزَلَتْ ( وَلِِلَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إِلَيْهِ سَبِيلاً ) قَالُوا يَا رَسُولَ اللَّهِ فِي كُلِّ عَامٍ فَسَكَتَ قَالُوا يَا رَسُولَ اللَّهِ فِي كُلِّ عَامٍ قَالَ لاَ وَلَوْ قُلْتُ نَعَمْ لَوَجَبَتْ فَأَنْزَلَ اللَّهُ ( يَا أَيُّهَا الَّذِينَ آمَنُوا لاَ تَسْأَلُوا عَنْ أَشْيَاءَ إِنْ تُبْدَ لَكُمْ تَسُؤْكُمْ )  

“When the following was revealed: “And Hajj (pilgrimage to Makkah) to the House (Ka’bah) is a duty that mankind owes to Allah, for whoever can bear the way.” [3:97] They asked: ‘O Messenger of Allah, is Hajj every year?’ He remained silent. They asked: ‘Is it every year?’ He said: ‘No. If I had said yes, it would have become obligatory.’ Then the following was revealed: “O you who believe! Ask not about things which, if made plain to you, may cause you trouble.’” [5:101]  

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 }  

When this verse ʿAnd Hajj (pilgrimage to Makkah) to the house (Kaʿbah) is a duty that mankind owes to Allah, those who can afford the expenses (for oneʿs conveyance, provision and residence)ʿ [Al-ʿImran 3:97] was revealed, they said: O Messenger of Allah ﷺ, is it every year? He remained silent. Then they said: Is it every year? He remained silent, Then they said: Is it every year? He said: ʿNo, if I said yes, it would be obligatory.ʿ Then Allah revealed the words: ʿO you who believe! Ask not about things which, if made plain to you, may cause you troubleʿ [Al-Ma’idah 5:101] up to the end of the Αyah.  

لَمَّا نَزَلَتْ هَذِهِ الْآيَةُ {وَلِلَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إِلَيْهِ سَبِيلًا} [آل عمران 97] قَالُوا يَا رَسُولَ اللهِ أَفِي كُلِّ عَامٍ؟ فَسَكَتَ فَقَالُوا أَفِي كُلِّ عَامٍ؟ فَسَكَتَ قَالَ ثُمَّ قَالُوا أَفِي كُلِّ عَامٍ؟ فَقَالَ لَا وَلَوْ قُلْتُ نَعَمْ لَوَجَبَتْ فَأَنْزَلَ اللهُ تَعَالَى {يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَسْأَلُوا عَنْ أَشْيَاءَ إِنْ تُبْدَ لَكُمْ تَسُؤْكُمْ} [المائدة 101] إِلَى آخِرِ الْآيَةِ  

" عَنْ عَلِىٍّ قَالَ: لَمَّا نَزَلَتْ هَذِه الآيَةُ {وَلِلَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إِلَيْهِ سَبِيلًا} وقَالُوا يَا رَسُولَ الله: أفِى كُلِّ عَامٍ؟ فَسَكَتَ، فَقَالُوا: أَفِى كُلِّ عَامٍ؟ فَسَكَتَ، ثُمَّ قَالُوا: افِى كُل عَامٍ؟ قَالَ: لاَ. وَلَوْ قُلتُ: نَعَمْ لَوَجَبَتْ، فأنْزَلَ الله {يَاأَيُّهَا آمَنُوا لَا تَسْأَلُوا عَنْ أَشْيَاءَ إِنْ تُبْدَ لَكُمْ تَسُؤْكُمْ} إِلَى آخِرِ الآيَةِ ".