תּלמוד אויף שופטים 16:17

דלילה saw that he had told all [that was in] his heart. How did she know? ר חנין said in the name of רב. True words are recognizable. אביי said, She knows about the righteous one that he would not utter the name of heaven in vain. As soon as he said "I am a nazir to G-d." Now she knew he was telling the truth.

Who dreams of shaving should on rising say, "And [Joseph] shaved himself and changed his raiment" (Gen. xli. 14), before another verse occurs to him, viz. : "If I be shaven, then my strength will go from me" (Judges xvi. 17). Who dreams of a well should on rising say, "A well of living waters" (Cant. iv. 15), before another verse occurs to him, viz. : "As a cistern welleth with her waters, so she welleth with her wickedness" (Jer. vi. 7). Who dreams of a reed should on rising say, "A bruised reed shall he not break" (Is. xlii. 3), before another verse occurs to him, viz. : "Behold, thou trustest upon the staff of this bruised reed" (ibid, xxxvi. 6).