The tension is greatest when the bob is at the bottom. The tension is least when the bob is at an endpoint.
Work Step by Step
The tension pulls the bob toward the center, radially, so it can only provide the centripetal force to the bob. When the bob is at the bottom, the tension acts upward and the weight is directed downward. The speed is greatest, and so is the required upward centripetal force. Tension must counteract gravity and provide this maximum centripetal force, so at this point it reaches its maximum value. At an endpoint, the bob is momentarily at rest and the centripetal acceleration is zero. The tension reaches its minimum value.