Prior to the 1973–74 NHL season, Henderson spoke to John Bassett, owner of the World Hockey Association (WHA)'s Toronto Toros. Bassett offered Henderson a five-year contract worth twice his annual $75,000 salary from the Maple Leafs. The deal included a $50,000 signing bonus and performance bonuses based on how he played in his final year with the Maple Leafs. Henderson signed the contract, though he said in his autobiography that he regretted doing so before completing his term with his NHL club. A bitter opponent of the WHA, Ballard had vowed not to lose more players to the rival league. When he found out about the deal, he offered Henderson the same contract terms, but without a signing bonus. Upset at how stingy Ballard had been with his teammates, Henderson told Ballard to "take this contract and shove it". An angered Ballard never forgave Henderson, and never spoke to him again.