According to Islam, ALL previous Prophets were also Muslims in the literal sense that they “submitted themselves to God.” Examples of this are in the Qur’an where Abraham, Moses, Jesus, Solomon, etc. are all called Muslims.
Qur’an 3:67: “Abraham was not a Jew nor yet a Christian; but he was true in Faith, and bowed his will to Allah's (Which is Islam), and he joined not gods with Allah.”
Qur’an 5:44: “It was We who revealed the law (to Moses): therein was guidance and light. By its standard have been judged the Jews, by the prophets who bowed (as in Islam) to Allah's will, by the rabbis and the doctors of law: for to them was entrusted the protection of Allah's book, and they were witnesses thereto: therefore fear not men, but fear me, and sell not my signs for a miserable price. If any do fail to judge by (the light of) what Allah hath revealed, they are (no better than) Unbelievers.”
Qur’an 5.111: "And behold! I (Allah) inspired the disciples (of Jesus) to have faith in Me and Mine Messenger (Jesus): they (the disciples) said, 'We have faith, and do thou bear witness that we bow to Allah as Muslims'".
Qur’an 27.44: “She (Queen of Sheba) was asked to enter the lofty Palace: but when she saw it, she thought it was a lake of water, and she (tucked up her skirts), uncovering her legs. He said: "This is but a palace paved smooth with slabs of glass." She said: "O my Lord! I have indeed wronged my soul: I do (now) submit (in Islam), with Solomon, to the Lord of the Worlds."
Qur’an 12.6: "Thus will thy Lord choose thee (Joseph) and teach thee the interpretation of stories (and events) and perfect His favour to thee and to the posterity of Jacob - even as He perfected it to thy fathers Abraham and Isaac aforetime! for Allah is full of knowledge and wisdom."
Qur’an 12.38: "And I (Joseph) follow the ways of my fathers,- Abraham, Isaac, and Jacob; and never could we attribute any partners whatever to Allah: that (comes) of the grace of Allah to us and to mankind: yet most men are not grateful.
Qur’an 2:132-133, “And Abraham charged his sons with this and Jacob likewise: 'My sons, God has chosen for you the religion; see that you die not, save in Islam (surrender).' Why, were you witnesses, when death came to Jacob? When he said to his sons, 'What will you serve after me?' They said, 'We will serve thy God and the God of thy fathers Abraham, Ishmael and Isaac, One God; to Him we surrender.'
Qur’an 2:140, “Or do you say, ‘Abraham, Ishmael, Isaac and Jacob, and the Tribes -- they were Jews, or they were Christians’? Say: ‘Have you then greater knowledge, or God? And who does greater evil than he who conceals a testimony received from God? And God is not heedless of the things you do.’
Qur’an 3:84, “Say: 'We believe in God, and that which has been sent down on us, and sent down on Abraham and Ishmael, Isaac and Jacob, and the Tribes, and in that which was given to Moses and Jesus, and the Prophets, of their Lord; we make no division between any of them, and to Him we surrender.'
Qur’an 4:163, “We have revealed to thee as We revealed to Noah, and the Prophets after him, and We revealed to Abraham, Ishmael, Isaac, Jacob, and the Tribes, Jesus and Job, Jonah and Aaron and Solomon, and We gave to David Psalms,”
Qur’an 38:45-47, “Remember also Our servants Abraham, Isaac and Jacob -- men of might they and of vision. Assuredly We purified them with a quality most pure, the remembrance of the Abode, and in Our sight they are of the chosen, the excellent.”
Qur’an 6:84-86, “And We gave to him Isaac and Jacob -- each one We guided, And Noah We guided before; and of his seed David and Solomon, Job and Joseph, Moses and Aaron -- even so We recompense the good-doers -- Zachariah and John, Jesus and Elias; each was of the righteous; Ishmael and Elisha, Jonah and Lot-each one We preferred above all beings;”
Qur’an 19:49-50, “So, when he went apart from them and that they were serving, apart from God, We gave him Isaac and Jacob, and each We made a Prophet; and We gave them of Our mercy, and We appointed unto them a tongue of truthfulness, sublime.”
Qur’an 21:72-73, “And We gave him Isaac and Jacob in superfluity, and every one made We righteous and appointed them to be leaders guiding by Our command, and We revealed to them the doing of good deeds, and to perform the prayer, and to pay the alms, and Us they served.”
Qur’an 29:27: “And We gave (Abraham) Isaac and Jacob, and ordained among his progeny Prophethood and Revelation, and We granted him his reward in this life; and he was in the Hereafter (of the company) of the Righteous.”
Qur’an 2:136, “Say you: ‘We believe in God, and in that which has been sent down on us and sent down on Abraham, Ishmael, Isaac and Jacob, and the Tribes, and that which was given to Moses and Jesus and the Prophets, of their Lord; we make no division between any of them, and to Him we surrender.’
Qur’an 19:54, “And mention in the Book Ishmael; he was true to his promise, and he was a Messenger, a Prophet.”
Qur’an 45:16-17, “Indeed, We gave the Children of Israel the Book, the Judgment, and the Prophethood, and We provided them with good things, and We preferred them above all beings. We gave them clear signs of the Command; so they differed not, except after the knowledge had come to them, being insolent one to another. Surely thy Lord will decide between them on the Day of Resurrection touching their differences.”