The Heart Sutra 'Joyous Elegant Speech'

So whether it is the present Buddha, a Buddha in the past or a Buddha yet to come, this result is due only to the Prajnaparamita. This refers not only to the Arya Buddha but also the other three types of Aryas. If the attainment of Buddhahood depends on Prajnaparamita then naturally the attainment of the level of Bodhisattva depends on it as well.