Source, in full
As quoted by Diogenes Laërtius, in Lives of Eminent Philosophers: 'Zeno', 7.87.: “This is why Zeno was the first (in his treatise On the Nature of Man) to designate as the end ‘life in agreement with nature’ (or living agreeably to nature)...”
Notes from Wikiquote
The "end" here means “the goal of life.”