قَعَدْتُ عَنِ الْحَرْبِ لِلْجُبْنِ
Translation: I stayed away from war because of cowardice.
قَعَدْتُ: verb with subject.
عَنِ الْحَرْبِ: prepositional phrase.
لِـ: causal preposition.
الْجُبْنِ: genitive after lām.
This is an added explicit reconstruction of the book’s “ay li-l-jubn”, not a verbatim full sentence from the source.