Sunan an-Nasa'i, Volume 3, Book 24, Hadith 2972 (DarusSalam) ⓘ
It was narrated that Jabir said: "When he went tout the Masjid heading for As-Safa, I heard the Messenger of Allah say: We will start with that with which Allah started.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ سَلَمَةَ، قَالَ أَنْبَأَنَا عَبْدُ الرَّحْمَنِ بْنُ الْقَاسِمِ، قَالَ حَدَّثَنِي مَالِكٌ، عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ، عَنْ أَبِيهِ، عَنْ جَابِرٍ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم حِينَ خَرَجَ مِنَ الْمَسْجِدِ وَهُوَ يُرِيدُ الصَّفَا وَهُوَ يَقُولُ " نَبْدَأُ بِمَا بَدَأَ اللَّهُ بِهِ " .
also referenced under: Hadith 2969 (Reference) & Book 24, Hadith 0 (In-Book)