Abu Dharr reported: I asked the Messenger of Allah, peace and blessings be upon him, about the first mosque placed on the earth. The Prophet said, “It was the Sacred Mosque.” I asked, “Then which one?” The Prophet said, “The furthest mosque in Jerusalem.” I said, “How long was between them?” The Prophet said, “Forty years, then the earth was made a mosque for you. Wherever the time for prayer reaches you, then pray there.”
Source: Ṣaḥīḥ al-Bukhārī 3366, Ṣaḥīḥ Muslim 520
Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim
عَنْ أَبِي ذَرٍّ قَالَ سَأَلْتُ رَسُولَ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ عَنْ أَوَّلِ مَسْجِدٍ وُضِعَ فِي الْأَرْضِ قَالَ الْمَسْجِدُ الْحَرَامُ قُلْتُ ثُمَّ أَيٌّ قَالَ الْمَسْجِدُ الْأَقْصَى قُلْتُ كَمْ بَيْنَهُمَا قَالَ أَرْبَعُونَ عَامًا ثُمَّ الْأَرْضُ لَكَ مَسْجِدٌ فَحَيْثُمَا أَدْرَكَتْكَ الصَّلَاةُ فَصَلِّ
3366 صحيح البخاري كتاب أحاديث الأنبياء باب حدثنا موسى بن إسماعيل
520 صحيح مسلم كتاب المساجد ومواضع الصلاة