fair-weather friend

asking for help

is one who lends you an umbrella when the weather is fair, and takes it back when it rains.

A fair-weather friend lends you an umbrella when the weather is fair, and takes it back when it rains.

is like a shadow in that it attends only when the sun shines.

A false friend and a shadow attend only when the sun shines.

is like a sundial: only marking the hours when the sun shines on you.

Many friends are like the sundial: they only mark the hours when the sun shines on you.