In Bank of America etc. Assn. v. Pendergrass (1935) 4 Cal.2d 258, the bank sued defendants to recover judgment on a promissory note in the sum of $ 4,750. Following opening statements, the trial court directed judgment in favor of the bank. Defendants appealed claiming that the bank had orally assured them it would not require them "'to make any payments on their indebtedness, either interest or principal, until the money came in from the 1932 crop of lettuce seed, and that the bank would permit them to go ahead and operate and produce this 1932 crop'." ( Id. at p. 263.) Finding that the alleged oral assurances were in direct contravention of the unconditional promise contained in the note to pay the money on demand, and thus constituted parol evidence, the appellate court barred the introduction of such evidence. ( Id. at pp. 263- 264.)