According to many studies, precise requests are very persuasive. This is because critical details create stronger impressions in our neural pathways than general requests.
An example of this may be a dialog such as, “Pay me before 5 p.m. on Saturday,” versus “Pay me on Saturday.” Or, “Brother, can you spare 37 cents,” rather than, “Got any spare change[vii].”
To counteract this deal tactic, create wiggle room: margins within which you are willing to work. For example, say, “We will pay you when we get paid.” Or a counteroffer of precise agreement, with a definitive endpoint such as “I agree, but no later than Tuesday.”