The only thing we have to fear is fear itself
belðuɾ is̻an beaɾ ðuɣun ɡaʊs̻a βakara βelðura ða
In Basque Beldur izan behar dugun gauza bakarra beldurra da
This is a direct translation of the original quote.
Example
"Krisiaren aurrean, gogoratu zuen: 'Beldur izan behar dugun gauza bakarra beldurra da'."