ENOfficial
Sulaiman b. 'Abd al-Rahman al-Dimashqi said about this tradition that al-Walid said: I heard Abu 'Amr al-Auza'i say: The word sirrahu means beginning of the month.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا سُلَيْمَانُ بْنُ عَبْدِ الرَّحْمَنِ الدِّمَشْقِيُّ، - فِي هَذَا الْحَدِيثِ - قَالَ قَالَ الْوَلِيدُ سَمِعْتُ أَبَا عَمْرٍو - يَعْنِي الأَوْزَاعِيَّ - يَقُولُ سِرُّهُ أَوَّلُهُ .
sunnah.com