Sforno on Exodus 26:6/ספורנו על שמות כ״ו:ו׳

1והיה המשכן אחד. Even though the respective level of sanctity of the two parts of the structure was not uniform, what they had in common was that both reflected the fact that the will of their Creator had been carried out. It reminds us of Isaiah describing different groups of angels calling to each other in mutual encouragement to proclaim the Holiness of G’d (Isaiah 6,3).