What is the meaning of the Prophet's (peace and blessings be upon him) saying: "Indeed, I have been given the Qur'an and something similar to it along with it"?

This hadith is one of the authentic hadiths that explain that Allah granted the Prophet another revelation, which is the Sunnah. This Sunnah interprets the Qur'an and clarifies its meaning. This revelation is for the completion of the message and the perfection of its delivery. The Prophet, peace and blessings be upon him, expressed it through the hadiths he explained to the Ummah, whether by word, deed, or tacit approval, such as the hadiths concerning actions being judged by intentions, and the unacceptability of prayer without ritual purity. This revelation also includes the Hadith Qudsi, which the Messenger narrates from his Lord; they are a revelation from Allah and from His words, but they do not have the same ruling as the Qur'an. An example of this is what he narrated from his Lord: (O My servants, I have forbidden injustice for Myself). All of this falls under Allah's saying: (Nor does he speak of [his own] inclination. It is not but a revelation revealed).