كتاب الصلاة
2  
The Book of Prayer
The first Hadith has a Shahid (supporting evidence) in the Hadith
فَإِنْ لِلْأَوَّلِ شَاهِدًا مِنْ حَدِيثِ :

Sunnah.com reference : Book 2, Hadith 199
English translation : Book 2, Hadith 0
Arabic reference : Book 2, Hadith 311