And when it was as if it was said: So they did not eat, it caused his saying: "Then he felt a fear". This means he concealed the state of his entire secret from them out of fear for their denial of not eating. For when he saw their aversion to the food, his imagination went to every possibility for their coming to him. They said, comforting him: "Do not fear" and informed him that they were messengers of Allah and gave him the good news of a boy, despite his old age and the despair of his wife due to her being past childbearing age, and that boy is Ishaq, peace be upon him. And since the context was for the concealment of the reasons, it was at the peak, and he described him with the saying: "Knowing". This means he is naturally predisposed and prepared for knowledge, and he will not die until his knowledge is manifested in action at its proper time.