I am returned - whereas in anger I had before withdrawn from her (Hos 5:15).
with mercies - not merely of one kind, nor once only, but repeated mercies.
my house shall be built - which at this time (the second year of Darius, Zec 1:1) had only its foundations laid (Hag 2:18). It was not completed till the sixth year of Darius (Ezr 6:15).
line - (Job 38:5). The measuring-line for building, not hastily, but with measured regularity. Not only the temple, but Jerusalem also was to be rebuilt (Neh 2:3, etc.; compare Zec 2:1, Zec 2:2). Also, as to the future temple and city, Eze 41:3; 42:1-44:31; Eze 45:6.