Sunnah.com reference : Book 2, Hadith 313English translation : Book 2, Hadith 403Arabic reference : Book 2, Hadith 408
Narrated Zaid bin Thabit (RA):
Allah's (ﷺ) made a small room of a mat (i.e. he used it to designate a space for prayer) and prayed inside it. The people followed him, and they came to pray behind him. The narrator mentioned the rest of the Hadith, and it contains the words: "The most excellent prayer of a person is (that which he prays) in his house except that which is prescribed (the five congregational prayers)."

[Agreed upon].
وَعَنْ زَيْدِ بْنِ ثَابِتٍ ‏- رضى الله عنه ‏- قَالَ: { اِحْتَجَرَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-حُجْرَةً بِخَصَفَةٍ, فَصَلَّى فِيهَا, فَتَتَبَّعَ إِلَيْهِ رِجَالٌ, وَجَاءُوا يُصَلُّونَ بِصَلَاتِهِ.‏.‏.‏ }  اَلْحَدِيثَ, وَفِيهِ: { أَفْضَلُ صَلَاةِ اَلْمَرْءِ فِي بَيْتِهِ إِلَّا اَلْمَكْتُوبَةَ }  مُتَّفَقٌ عَلَيْه ِ  1‏ .‏‏1 ‏- صحيح.‏ رواه البخاري (731)‏، ومسلم (781)‏.‏