John Gill Commentary 1 Kings 8:54

"And it was so, that, when Solomon had made an end of praying all this prayer and supplication unto Jehovah, he arose from before the altar of Jehovah, from kneeling on his knees with his hands spread forth toward heaven." — 1 Kings 8:54 (ASV)

And it was so, that, when Solomon had made an end of praying
all this prayer and supplication unto the Lord
In which he was a type of Christ, praying and interceding for his people before the golden attar, (Revelation 8:3Revelation 8:4) ,

he arose from before the altar of the Lord ;
the altar of burnt offering, over against which he was:

from kneeling on his knees ;
upon the brasen scaffold; see (2 Chronicles 6:13) , in which posture he was during this long prayer:

with his hands spread up to heaven ;
which gesture he had used in his prayer, and now continued in blessing the people.