“Blessed ones, those who have been persecuted for righteousness' sake,
For theirs is the Kingly Rule of Heaven.”
Here those who are blessed by God ‘have been persecuted for righteousness' sake'. This can hardly refer to His current disciples, for they are hardly yet in a position to have faced any real level of persecution. And if it had been meant to refer to them, why the change of tense? Thus the blessed ones spoken of are in the past, which is confirmed by the introduction of the present listeners in Matthew 5:11. For John, who is specifically said to have ‘come in the way of righteousness' (Matthew 21:32), had certainly been persecuted ‘for righteousness' sake', and we may see it as very probable that some of his faithful disciples had suffered with him in one way or another. They would not have sat idly by while he was hauled off to prison, and they may well have been roughly handled when they visited him, as very bravely they continued to do (Matthew 11:2). And they may also have come in for mistreatment in the synagogues as well, in the same way as Jesus' disciples would later. So Jesus may here be pointing His disciples in that direction as an example.
The past tense may, however, also be seen as including the prophets (who are specifically referred to in Matthew 5:12) and others who in the past have suffered ‘for righteousness' sake'. There were in fact no lack of heroes of the faith in the past (Hebrews 11:35-38). And that such would enjoy the Kingly Rule of Heaven is implicit in Matthew 8:11 where Abraham, Isaac and Jacob are also seen as enjoying it. If this is so then this reference to the persecution of others in the past is a timely warning to His disciples of what they too can expect (see Matthew 10:17-23), and an assurance that the saints of the past will not lose out, any more than they will. (It also confirms the exclusion of this beatitude from the original list of beatitudes). And the whole point is that these things happened to God's blessed ones in the past, with the consequence being their enjoyment of His Kingly Rule. This is then ample confirmation that His present blessed ones will experience the same.
The persecution of the prophets is a clear theme in 2 Chronicles 36:16, see also 1Ki 19:10; 1 Kings 19:14; Nehemiah 9:26; Jeremiah 2:30, so that Jesus was by no means the first to draw attention to it (Matthew 21:34-36; Matthew 23:29-31; Matthew 23:35). Indeed, as He points out, the persecutors drew attention to it themselves (Matthew 23:30). Jesus is thus aligning His present disciples with the past, as part together of all God's purposes through history.