Have you ever noticed the differences between the wording in the verse which follows, in each of the passages where this phrase (in your quoted verse ^ ) is found?
Each of the verses which follow, sound as though they are expressing DISTINCT things from each other (I underlined those):
Matthew 10 -
[note: set in the context of vv.5-7, which says, "5 These twelve, Jesus sent forth, having instructed them, saying: “Do not go into the way of the Gentiles and do not enter into any city of the Samaritans. 6 But go rather to those being the lost sheep of the house of Israel. 7 And going on, proclaim, saying, ‘The kingdom of the heavens has drawn near!’"]
26 Therefore you should not fear them! For nothing is concealed that will not be revealed, or hidden that will not be known. 27 What I tell you in the darkness, speak in the light; and what you hear in the ear, proclaim upon the housetops!
Luke 12 -
1 In these times, the myriads of the crowd having been gathered together so as to trample upon one another, He began to say to His disciples first, “Take heed to yourselves of the leaven of the Pharisees, which is hypocrisy. 2 And nothing is concealed up which will not be revealed, nor hidden which will not be known. 3 Instead, whatever you have said in the darkness will be heard in the light, and what you have spoken into the ear in the inner rooms will be proclaimed upon the housetops.