ENOfficial
Samura b. Jundub said that the war-cry of the Emigrants was ‘Abdallah and that of the Helpers ‘Abd ar-Rahman. Abu Dawud transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَن سَمُرةَ بن جُندبٍ قَالَ: كَانَ شِعَارُ الْمُهَاجِرِينَ: عَبْدَ اللَّهِ وَشِعَارُ الْأَنْصَار: عبدُ الرَّحمنِ. رَوَاهُ أَبُو دَاوُد
sunnah.com