Verily We have sent thee (Muhammad) in truth as a bearer of glad tidings and as a warner: And there never was a people without a warner having lived among them (in the past). Qur’an 35:24
For We assuredly sent amongst every People an apostle (with the Command) “Serve Allah and eschew Evil”: Of the people were some whom Allah guided and some on whom Error became inevitably (established). So travel through the earth and see what was the end of those who denied (the Truth). Qur’an 16:36
And Messengers (Prophets who received revealed books) We have mentioned unto thee (Muhammad) before And Messengers We have not mentioned unto thee; And Allah spoke directly unto Moses. Qur’an 4:164
These verses of the Holy Qur’an testify that Allah (the One True God) has sent prophets to every people. Therefore, it is not surprising to Muslims to find prophecies about the Last Prophet, Muhammad (s), in previously revealed scriptures. Moreover, Allah had taken covenant with the Prophets to believe and help future Prophets of Allah, as indicated by the verse quoted below.
Allah’s Covenant With Prophets
Behold! Allah took the covenant of the Prophets saying: “I give you a Book and Wisdom; then comes to you an Apostle confirming what is with you; do ye believe him and render him help.” Allah said: “Do ye agree and take this My Covenant as binding on you?” They said: “We agree.” He said: “Then bear witness and I am with you among the witnesses.” If any turn back after this they are perverted transgressors. Qur’an 3:81-82