Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, was delivering a sermon and he said, “O people, the Hajj pilgrimage has been made an obligation, so undertake it.” A man said, “O Messenger of Allah, is it every year?” The Prophet remained silent until the man repeated his question three times. Then, the Prophet said, “If I had said yes, it would have been required and you would not be able to do it.”
Source: Ṣaḥīḥ Muslim 1337
Grade: Sahih (authentic) according to Muslim
عَنْ أَبِي هُرَيْرَةَ قَالَ خَطَبَنَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ أَيُّهَا النَّاسُ قَدْ فَرَضَ اللَّهُ عَلَيْكُمْ الْحَجَّ فَحُجُّوا فَقَالَ رَجُلٌ أَكُلَّ عَامٍ يَا رَسُولَ اللَّهِ فَسَكَتَ حَتَّى قَالَهَا ثَلَاثًا فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَوْ قُلْتُ نَعَمْ لَوَجَبَتْ وَلَمَا اسْتَطَعْتُمْ
1337 صحيح مسلم كتاب الحج باب فرض الحج مرة في العمر