bite the hand that feeds one

all bark and no bite

Full of big talk but lacking action, power, or substance; pretentious.

as best one can

In the best possible way, given one's circumstances and abilities.

as far as one knows

To the best of one's knowledge, as far as someone knows or possible information to be gathered about the topic, subject, aspect, or situation.

back of one's hand

A display of disrespect or scorn.

back to square one

Located back at the start, as after a dead end or failure.

bear a hand

To make haste; to help quickly.

beat as one

To share the same feelings.

become one flesh

To join together in marriage; to develop a unifying bond as a result of marrying.