قَعَدْتُ عَنِ الْحَرْبِ جُبْنًا
Translation: I stayed away from war out of cowardice.
قَعَدْتُ: past verb built on sukūn with -tu as its subject.
عَنْ: preposition.
الْحَرْبِ: genitive after ʿan; the phrase relates to qaʿadtu.
جُبْنًا: accusative complement expressing the reason.
The phrase ʿani l-ḥarbi states what was avoided; jubnan states why.