After the first revelation in the Cave of Hira, the revelation stopped for a while. This pause is known as fatrat al-wahy. Accounts differ on how long it lasted. Some say two or three years, but this is considered far too long. A narration from Ibn Abbas puts it at 40 days, and Ibn Shihab al-Zuhri described it as around a month. Together they suggest it lasted about a month and ten days.
During this time, Muhammad ﷺ was troubled. He later said, "I was worried for myself," meaning that he feared he was imagining things. Every day he went to Jabal al-Nour, the mountain of the cave, hoping to see the angel Jibril again, but he found nothing there.
Then one day, as he was walking, he heard a sound and looked up. He saw the same angel he had seen in the cave, seated on a throne between the heavens and the earth. Trembling again, he rushed home to his wife Khadija RA and asked her to wrap him up. Jibril did not speak to him out on the mountain. He followed him home, and only once Muhammad ﷺ was wrapped up in Khadija's house did Jibril reveal the opening verses of Surah al-Muddaththir (Qur'an 74:1-7).
Scholars suggest that the pause served to prepare him for what was coming, letting him recover and feel ready for the mission. Even so, he still trembled with fear when Jibril appeared to him again. This very human reaction is held up as evidence that he was not inventing his prophethood. Someone making a false claim tells grand stories in which he is the hero, and would not describe himself this way.