In The Quran
(2:185) The month of Ramadan, in which the Quran was sent down as a guide to the people and a clarification of the guidance and the criterion. Therefore, those of you who witness (arab. شَهِدَ, shahida) the month shall fast therein. Whoever is ill or traveling, then the same number from different days. God wants to bring you ease and not to bring you hardship; and so that you may complete the count, and glorify God because He has guided you, that you may be thankful.
(3:81) God took a covenant from the prophets: "For what I have given you of the book and philosophy, then a messenger will come to you authenticating what is with you. You will acknowledge him and support him." He said, "Do you testify, and agree to this burden?" they said, "We testify." He said, "Then bear witness (Arab. فَاشْهَدُوا, fa-ish'hadū), and I am with you bearing witness."
To bear witness
(41:53) We will show them Our signs in the horizons, and within themselves, until it becomes clear to them that this is the truth. Is it not enough that your Lord is witness (Arab. شَهِيدٌ, shahīdun) over all things?