At many moments throughout the book, the narrator takes a moment to specifically describe the dawning of a new day or the end of one in a sunset. This is, on a simple level, a way to move the story forward to the next day, a way to indicate in an interesting way that one day in the story has ended and another has begun.
Oftentimes the sun is personified in these descriptions, as at the beginning of the book. Janie begins telling her story to Pheoby in the evening: "The sun was gone, but he had left his footprints in the sky." This is quite a picturesque image of a sunset, describing it as the sun's footprints. Sometimes these moments are not personifications of the sun, but of morning: “Every morning the world flung itself over and exposed the town to the sun. So Janie had another day.” Or, as later in the book, the sunlight is personified instead: "Daylight was creeping around the cracks of the world when Janie heard a feeble rap on the door."
These repeated structures lend a consistent sense of time to the book. The reader understands how the story moves forward, day by day. This is especially important in a story with a complicated structure of time, in its frame narrative, and in a story which sometimes leaps years ahead. These references to daylight are also perhaps a subtle allusion to similar references at the beginning of many of the books of Homer's Iliad and Odyssey, which describe a personified Dawn which lights each new day. In sum, these references help to structure the book, but do so in a nuanced and aesthetically appealing way.
Hurston alludes to Michal in the Book of Samuel after Janie calls Joe fat, old, ugly, and vain, in public:
Then Joe Starks realized all the meanings and his vanity bled like a flood. Janie had robbed him of his illusion of irresistible manliness that all men cherish. The thing that Saul's daughter had done to David. But Janie had done worse, she had cast down his empty armor before men and they had laughed, would keep on laughing.
After Janie insults Joe, he is thoroughly taken aback. He, perhaps for the first time, has become aware that he is getting uglier with old age. Hurston then compares Janie's insult to "the thing that Saul's daughter had done to David." She is referring to when Michal, daughter of Saul in the Bible, publicly taunted David, her husband, for dancing in an undignified way in public; Michal was then cursed to have no children. Allusions, especially biblical ones, are often used as the paragon, the pinnacle, of some action or virtue. But then Hurston says this is even worse than what Saul's daughter did to David. She downplays the curse on Michal by calling it "the thing." Janie's insult, in contrast, is much worse. Hurston quietly extends the allusion in the next sentence: Michal insulted David after he cast down his armor and danced in the streets following a military victory. But Hurston shows, in this sentence, why Janie "had done worse" than Michal: she not only laughed at Joe, but she was the one who "cast down his empty armor." In other words, Michal only laughed at her embarrassing husband; Janie embarrassed her husband herself, then laughed at him. The allusion allows Hurston to describe the magnitude of Janie's rudeness to her husband.
But even still, at a deeper level, there's a bit of tongue-in-cheek wryness in the way that Hurston phrases "The thing that Saul's daughter had done to David." There is an implication that male embarrassment is not all that serious of a problem. The reader remembers that Janie is supposed to be telling this story. Janie uses the story from Samuel to hyperbolically criticize herself, showing ironically that Joe Starks is really being rather melodramatic in his reaction to Janie's insult.
Tea Cake makes a quick allusion to the Gospel of Matthew while flirting with Janie in one of their first meetings. He says he'd buy her anything she wants, even a battleship or a passenger train, and when Janie doubts he could acquire a battleship, he says:
Ah shucks, dem Admirals is always ole folks. Can't no ole man stop me from gittin' no ship for yuh if dat's what you want. Ah'd get that ship out from under him so slick till he'd be walkin' on de water lak ole Peter befo' he knowed it.
This is a subtle reference to Matthew 14:28–29. This is the famous story of Jesus walking on water. Jesus's disciples see him walk on water and do not believe that it is him. Peter asks Jesus to prove that it is really him walking on water: "Peter answered him and said, 'Lord, if it be thou, bid me come unto the water.' And he said, 'Come.' And when Peter was come down out of the ship, he walked on the water, to go to Jesus." So Peter, too, walked on water, due to the power of Jesus.
Tea Cake is making a very subtle and specific allusion here. Note that Tea Cake doesn't compare the admirals to Jesus walking on water, which is the more familiar reference. He instead alludes to Peter, because he was compelled to walk on water and Jesus did so of his own free will—like Tea Cake will compel the admiral to walk on water after taking his boat. This allusion has a variety of effects. For one, it shows Tea Cake's strong self-confidence, as he is essentially calling himself Jesus, since he would make the admirals walk on water like Peter did. (Hurston doesn't comment on whether Tea Cake is aware of this implication, or whether Janie notices.)
The allusion, which would require an intimate knowledge of the Gospels, also shows that Tea Cake had a Christian upbringing, or at least knows the Bible quite well. This contrasts with his sinful nature as a drifter, drinker, and gambler. Perhaps his allusion is meant to impress Janie by showing her that despite all the lavish gifts he would give her, he still is a faithful Christian who will treat her well. And, at its core, the allusion is one of the best examples of Tea Cake's quick-talking ways that so flatter Janie. He is at once flirting with her, making a swift and funny joke, and making a well-read allusion. It is this ability to talk that, at first, makes Janie fall for him.