And then the sign of the Son of Man will appear in the sky (ouranō | οὐρανῷ | dat sg masc), and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of the sky (ouranou | οὐρανοῦ | gen sg masc) with power and great glory.
Reference
Matthew 24:30
Sequence
65