What is the evidence from the Qur'an for the secret stage of the call, lasting 3 years?

The Prophet's call, in its initial stage, was secret for three years, limited to individual دعوت (preaching/invitation) without openly proclaiming it. There is no explicit Quranic proof for this, except that some exegetes, like Ibn Kathir, mentioned on the authority of Ibn Mas'ud that the Prophet ﷺ remained hidden until the verse was revealed: "Therefore, proclaim what you have been commanded and turn away from the polytheists. Indeed, We will suffice you against the mockers" (Quran 15:94-95). After this, he and his companions emerged.