The trial period was ten days. At the end of the test, Daniel and his friends appeared healthier than those eating the royal food, so the steward continued their diet. Daniel 1:12–16
In Daniel 1:11–14, Daniel addresses the attendant assigned to oversee him and his three friends and asks for a limited trial. He proposes ten days of a simple diet—vegetables and water—in place of the royal food. After the ten days, the attendant should compare their appearance with that of the youths eating the king’s food and then decide how to proceed. This scene continues the opening story of Daniel and other Judean youths brought into the Babylonian court for training (Daniel 1). Just before this, Daniel has expressed a resolve not to “defile” himself with the king’s food and wine and has requested an alternative arrangement.
Daniel makes a careful request through the proper chain of authority: he speaks to the steward assigned over the four Judean youths. He proposes a limited, time-bound test—ten days—where they eat “pulse” and drink water instead of the king’s food.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Daniel 1:12-16, then read the surrounding section so the answer stays connected to the passage's flow.
12Prove your servants, I beg you, ten days; and let them give us pulse to eat, and water to drink.
13Then let our faces be looked on before you, and the face of the youths who eat of the king`s dainties; and as you see, deal with your servants.
14So he listened to them in this matter, and proved them ten days.
15At the end of ten days their faces appeared fairer, and they were fatter in flesh, than all the youths who ate of the king`s dainties.
16So the steward took away their dainties, and the wine that they should drink, and gave them pulse.