Surah 6. Al-An'am, Ayah 124

I.e., direct revelation.

Besides the teaching in God's Word, and the teaching in God's world, of nature and history and human contacts, many Signs also come to the ungodly, in the shape of warnings or otherwise, which the ungodly either do not heed, or deliberately reject. The Signs in the two cases are not the same, and that becomes one of their perverse arguments against Faith. But God's working will be according to His own Will and Plan, and not according to the wishes whims of the ungodly.