仁王經疏 3.63

3.63

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?