If it has been adequately established, both historically from the Scriptures and the tradition that they inform and by which they are informed and with which Jesus would have been familiar, as well as within the context of the sermon on the mount, that purity of heart is related to money (treasure) and its use, it is possible to then go on to discern, based on that understanding, what it might mean to “see God.”
To determine what this means, it is necessary to look outside the sermon on the mount, realizing that the sermon of chapters five, six, and seven serve as the foundation of what is going to be seen and hear from Jesus throughout the remainder of Matthew’s Gospel. That is a completely understandable and plausible assertion, as when one read a story that is presented in narrative form, as Matthew’s presentation of Jesus most certainly is, the reader knows that the things that are seen and heard and read early in the story will inform an understanding of what comes later, just as what comes later generally allows a reader to interpret that which has already been encountered.
With that said, it is possible to turn to the twenty-fifth chapter of Matthew. In the thirty-first verse of this chapter, Jesus is heard speaking. He says “When the Son of Man comes in His glory and all the angels with Him, then He will sit on His glorious throne.” Now it is obvious that Jesus is here speaking of Himself. Prior to this, Matthew presents Jesus speaking of Himself as the Son of Man on twenty-three occasions. After this usage, there will be an additional four, all found in the twenty-sixth chapter, thus making for a total of twenty-eight self-references by Jesus as the Son of Man.
When Jesus speaks of the Son of Man in conjunction with coming in glory, angels, and a throne, He is making explicit reference to the Son of Man of Daniel chapter seven. Looking to Daniel, one finds “I was watching in the night visions, And with the clouds of the sky one like a son of man was approaching. He went up to the Ancient of Days and was escorted before Him. To Him was given ruling authority, honor, and sovereignty. All peoples, nations, and language groups were serving Him. His authority is eternal and will not pass away. His kingdom will not be destroyed” (7:13-14).
When one hears reference to the Son of Man, especially at this juncture in Matthew’s work (though really throughout the entirety of the work), the reference demands to be heard in the context of and in connection with the kingdom of heaven. This Son of Man is given rule over all. He rules over the kingdom of the Creator God, which is an interchangeable term with kingdom of heaven, with both meaning the same thing (the Creator God’s will being done on earth as in heaven, through the agency of covenant members). Since it is the Creator God Himself that is understood to ultimately rule His kingdom, then it is quite safe to say (though this probably needs far more qualifications and explanations), that the Son of Man, though not the Ancient of Days, and though He is not necessarily supposed to be looked to as “God the Father” (to use a Trinitarian term), is of a piece with the Creator God.
Naturally, as the Matthean narrative is compiled from a post-Resurrection perspective in which Jesus is worshiped as the Son of God and the Messiah (the manifestation of the Creator God in the flesh), the term “Son of Man” is quite naturally and overtly bestowed with divine attributes. Put simply, if Jesus is understood to be the manifestation of the Creator God, and if He calls Himself the Son of Man, then the Son of Man can be understood to be the Creator God.