oscillations in ada4897-1 o/p

I am using the above mentioned opamp as a unity gain amplifier and the opamp is powered from 5V supply (Single supply). I am seeing oscillations in the o/p if opamp when a dc or ac input  is given to opamp. can any one suggest the reason. i have provided proper decoupling and the amplifier is not driving any load through out the test, opamp is unity gain stable.