George Haydock's Catholic Bible Commentary - Revelation 3:7-13
To the Angel of the church of Philadelphia. There were several towns of this name; here is understood that which was near Sardis, in Lydia. Here is no more than an admonition to persevere, to hold that which thou hast. Christ takes the title of the Holy One, and True One, who hath the key of David; i.e. being the son of David, and the promised Messias, hath the supreme power in the Church: who opens the gate of salvation, and no one shuts it against his elect. (Witham) --- By the key in this... read more
Hawker's Poor Man's Commentary - Revelation 3:7-13
(7) And to the angel of the church in Philadelphia write; These things saith he that is holy, he that is true, he that hath the key of David, he that openeth, and no man shutteth; and shutteth, and no man openeth; (8) I know thy works: behold, I have set before thee an open door, and no man can shut it: for thou hast a little strength, and hast kept my word, and hast not denied my name. (9) Behold, I will make them of the synagogue of Satan, which say they are Jews, and are not, but do lie;... read more