Allah, Most High, has decreed Hajj for you. Al-Aqra' bin Habis At-Tamimi said: "Every year, O Messenger of Allah?" But he remained silent, then he said: "If I said yes, it would become obligatory, then you would not hear and obey. Rather it is just one Hajj." (Using translation from Nasāʾī 2620)
أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ «يَا قَوْمُ كُتِبَ عَلَيْكُمُ الْحَجُّ» فَقَالَ الْأَقْرَعُ بْنُ حَابِسٍ أَكُلَّ عَامٍ يَا رَسُولَ اللَّهِ؟ فَصَمَتَ رَسُولُ اللَّهِ ﷺ ثُمَّ قَالَ لَا بَلْ حَجَّةً وَاحِدَةً ثُمَّ مَنْ حَجَّ بَعْدَ ذَلِكَ فَهُوَ تَطَوُّعٌ وَلَوْ قُلْتُ نَعَمْ لَوَجَبَتْ عَلَيْكُمْ ثُمَّ إِذًا لَا تَسْمَعُونَ وَلَا تُطِيقُونَ