ISB ~ Revelation 10 v3

a lion roaring:The angel speaks the words of Christ, the Lion of Judah (5:5; cf. Is 31:4; Hos 11:10; Amos 3:8).

seven thunders:The mighty voice of the Lord (Ps 29:3-9). It may be linked with the Spirit, who earlier appears as “seven spirits” (1:4) and “seven torches” (4:5).