MSP430I2040: what is the requirement of capacitor connected at VREF pin when external voltage reference is used?

Tool/software:

Hi,

In the datasheet, it is stated that a 100nF capacitor must be connected at VREF pin when internal reference is used, but nothing is said about such capacitor when external reference is used. Could someone please clarify if such capacitor is still needed?

Thanks,

ZL