Anas (May Allah be pleased with him) reported:
Whenever the Messenger of Allah (ﷺ) set out to participate in Jihad, he would supplicate: "Allahumma Anta 'adudi wa nasiri, bika ahulu, wa bika asulu, wa bika uqatilu (O Allah, You are my Supporter and my Helper. With Your help I get strength, and with Your help I bounce upon the enemy and defeat it, and with Your help I fight)."[Abu Dawud and At- Tirmidhi]. (IT)
App reference (IT): Book 12, Hadith 42 (IT)
Arabic/English book reference (IT): Book 12, Hadith 1326 (IT)