اللَّهُمَّ أَنْتَ عَضُدِي، وَأَنْتَ نَصِيرِي، بِكَ أَحُولُ وَبِكَ أَصُولُ، وَبِكَ أُقَاتِلُ
O Allah, You are my strength and You are my support. For Your sake I go forth and for Your sake I advance and for Your sake I fight.
Allaahumma 'Anta 'adhudee, wa 'Anta naseeree, bika 'ajoolu, wa bika 'asoolu, wa bika 'uqaatilu.
Abu Dawud 3/42, At-Tirmithi 5/572. See also Al-Albani, Sahih At-Tirmithi 3/183.