仁王經疏 3.63

3.63

釋曰：第二兩頌偈釋諸苦相。文別有二：初一偈半正明諸苦、後有半偈舉勝況劣。前中有三：初有兩句明其四苦相續不絕；次有二句通顯三苦，謂怨憎會苦、愛別離苦、求不得苦，皆與願違，或是憂悲為害；後有二句明五盛蘊苦。諸欲是集諦，禍重是苦，如是苦集猶如瘡疣。如是苦集，不離自身、不出三界，故言無外。三界皆苦國有何樂者，舉勝況劣。謂三界勝劣皆悉是苦，況其國土何賴非苦？

Explanation: The second two verses explain the characteristics of the various sufferings. The text is divided into two parts: first, one and a half verses directly explain the various sufferings; second, half a verse compares the superior to highlight the inferior.
Within the former there are three parts: first, two lines explain that the four sufferings continue unbroken; next, two lines generally display three sufferings—namely, the suffering of meeting the hated, the suffering of separation from the loved, and the suffering of not getting what is sought—which all go against one's wishes, or are harms caused by worry and sorrow; and finally, two lines explain the suffering of the five clinging aggregates.
The various desires are the truth of origin (samudaya-satya); grave calamities are suffering (duḥkha-satya). Such suffering and origin are like ulcers and warts. Such suffering and origin are not separated from one's own body and do not transcend the three realms; hence it is said "nothing outside."
As for "The three realms are all suffering; what joy is there in a kingdom?": this compares the superior to highlight the inferior. It means that both the superior and inferior within the three realms are all entirely suffering; how much more so could their kingdom be relied upon as non-suffering?