A rule that a sale or proof-of-value engagement should never be pushed onto a customer — the customer's own pull, i.e. independent motivation to move the deal forward, must be present, and Herzberg holds this applies even as a company scales well past its earliest deals. If a deal only advances because the vendor is chasing, convincing, or nudging the prospect rather than the reverse, that's a signal the deal isn't real and further resourcing should be withheld. Operationalized via B2B Buying-Signal Checklist (Pricing, PO Timeline, Internal Introductions) and High-Effort Ask as a Commitment Filter, and consistent with Affirmation Bias vs. Disconfirming-Feedback Bias (Customer Discovery)'s warning against mistaking politeness for demand.