Mat 10:29 Are not two sparrows sold for a penny? and one of them shall not fall on the ground without your Father.

This verse seems like a change of subject from the previous verse about people being able to kill your body but not your soul, but looking at the Greek, it is a clear continuation of that idea.

"Sparrows" is strouthion, which actually means a "tiny sparrows" from strouthos, "sparrow." These were sold at the temple as the least expensive animal sacrifices.

"Sold" is from poleo, which means "to exchange" and "to barter." When this word is applied to people (as it is metaphorically here), it means "to betray" or "to give up."

"Penny" is from assarion, which was one-tenth of a drachma, which was the standard silver coin of Greece.

"Fall" is pipto, which means "to fall" and "to fall down." It is the root word for dozens of Greek terms involving moving from a higher state to a lower one. Like our word "to fall" it has a number of special meanings including "to fall into a given class," "to prostrate," "to fall from power," "to perish," and so on.

"Ground" is "ge" which means "earth." Like our word "earth" it can mean "the whole planet," "the ground," or "arable land."

"Without" is aneu, which means "without," "far from," and "except."

The ideas here are that:
The smallest creatures are sold for little money as a sacrifice.
The smallest people are betrayed for practically notihng for religious reasons.
Not even the smallest can be brought down to earth without God's permission.