Which passage are you thinking suggests that he went as far as jhana? This is the closest I could find:
“Seeing therefore, that all our former labour of the braine, is only to affect the heart; after that the minde hath thus trauersed the point proposed throgh all the heads of reason, it shall indeuour to find in the first place some feeling touch, & sweete rellish in that which it hath thus chewed; which fruit, through the blessing of God will voluntarily follow upon a serious Meditation.”
https://quod.lib.umich.edu/e/eebo/A02513.0001.001/1:4.28?rgn=div2;view=fulltextBTW there are other suggestions of jhana-like pleasure in Christian meditation. This is from
De Incendio Amoris by the 14th century English writer Richard Rolle:
"I was sitting in a certain chapel, and being much delighted with the sweetness of prayer or meditation, suddenly I felt in me a strange and pleasant heat."