Sunan an-Nasa'i
Book 8: The Book of the Masjids
كتاب المساجد
54 hadith in this book
Chapter 37 The Command To Pray Before Sitting Down In It
باب الأَمْرِ بِالصَّلاَةِ قَبْلَ الْجُلُوسِ فِيهِ
It was narrated from Abu Qatadah that the Messenger of Allah (ﷺ) said: "When any one of you enters the Masjid, let him pray two Rak'ahs before he sits down."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا مَالِكٌ، عَنْ عَامِرِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، عَنْ عَمْرِو بْنِ سُلَيْمِ، عَنْ أَبِي قَتَادَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا دَخَلَ أَحَدُكُمُ الْمَسْجِدَ فَلْيَرْكَعْ رَكْعَتَيْنِ قَبْلَ أَنْ يَجْلِسَ " .
Hadith text, translations and grading are courtesy of Sunnah.com.