What is the interpretation of Allah Almighty's saying: "And the earth – We have spread it out and cast therein firmly set mountains and caused to grow therein [something] of every beautiful kind," and does "cast therein" mean that the mountains were cast down from the sky?

"And We cast therein firm mountains" means We made firm mountains therein, for "casting" here means making and creating, not sending down mountains from the sky, as was narrated in the Hadith of Abu Hurayrah (may Allah be pleased with him) that Allah created the mountains on Sunday.