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You can never be too careful when choosing friends.
Literal
Friend [object-を] choose time [at-には] however-much careful-even excess is-not.
どれだけ ('however much, no matter how much') is interchangeable here with いくら or どんなに in the 'one can never X too much' construction. The idiom literally says 'careful' + 過ぎる ('exceed') + 過ぎることはない ('never exceeds'), giving 'no amount of caution is excessive.'