That is a very good question.  Let’s look at a few examples where the Lord told His disciples not to tell anyone what had happened. 

In Mark 7:31-37 we read, “And again, departing from the coasts of Tyre and Sidon, he came unto the sea of Galilee, through the midst of the coasts of Decapolis. And they bring unto him one that was deaf, and had an impediment in his speech; and they beseech him to put his hand upon him. And he took him aside from the multitude, and put his fingers into his ears, and he spit, and touched his tongue; And looking up to heaven, he sighed, and saith unto him, Ephphatha, that is, Be opened. And straightway his ears were opened, and the string of his tongue was loosed, and he spake plain. And he charged them that THEY SHOULD TELL NO MAN: but the more he charged them, so much the more a great deal they published it; And were beyond measure astonished, saying, He hath done all things well: he maketh both the deaf to hear, and the dumb to speak.” 

In Matthew, chapter 17, the Lord was transfigured in front of Peter, James, and John.  There, the Lord’s “face did shine as the sun, and his raiment was white as the light.” (Verse 2).  After this incredible event, we read in verse 9, “And as they came down from the mountain, Jesus charged them, saying, TELL THE VISION TO NO MAN, until the Son of man be risen again from the dead.”  The Lord tells His disciples not to tell of this vision until He had died and risen again from the dead.  It is Peter who later speaks of this event in 2 Peter 1:16-19, “For we have not followed cunningly devised fables, when we made known unto you the power and coming of our Lord Jesus Christ, but were eyewitnesses of his majesty. For he received from God the Father honour and glory, when there came such a voice to him from the excellent glory, This is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount. We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts.” 

Besides these, there are several other instances where the Lord Jesus instructed others to ‘tell no man’ what they had seen or heard from Him.  Why would the Lord want to keep His actions secret?  Let us consider one more example, which may help us understand why the Lord issued such a command.  We read in Mark 1:40-44, “And there came a leper to him, beseeching him, and kneeling down to him, and saying unto him, If thou wilt, thou canst make me clean. And Jesus, moved with compassion, put forth his hand, and touched him, and saith unto him, I will; be thou clean. And as soon as he had spoken, immediately the leprosy departed from him, and he was cleansed. And he straitly charged him, and forthwith sent him away; And saith unto him, See thou SAY NOTHING TO ANY MAN: but go thy way, shew thyself to the priest, and offer for thy cleansing those things which Moses commanded, for a testimony unto them.”  Here again, the Lord instructed this healed leper to tell no one.  This man, possibly due to his thankfulness and excitement disregarded the Lord’s instructions and began to tell others of this miracle.  Now, let’s read verse Mark 1:45, “But he went out, and began to publish it much, and to blaze abroad the matter, insomuch that Jesus could no more openly enter into the city, but was without in desert places: and they came to him from every quarter.”  When the Lord’s miracle was heard of, the people crowded Him so much that He could not even enter the city.  Even in the desert, people came to Him.  So, we learn the reason why Christ did not wish the miracles to be made known so soon. It was that he might have more abundant opportunity and freedom for teaching.  We also read that many people followed the Lord only because of the miracles He did.  John 2:23-25 tells us, “Now when he was in Jerusalem at the passover, in the feast day, many believed in his name, when they saw the miracles which he did. But Jesus did not commit himself unto them, because he knew all men, And needed not that any should testify of man: for he knew what was in man.”  The Lord discerned that these people had no faith, they were just following Him to see Him do spectacular things. 

The Lord did tell some to tell others about Him and His miracles.  In Mark, chapter 5, the Lord healed a man who had so many demons that he was called Legion.  After driving the demons out of Legion, the Lord said to him in verse 19, “Go home to thy friends, and tell them how great things the Lord hath done for thee, and hath had compassion on thee.” 

It seems to depend upon the circumstances whether the Lord told His people to spread the news of His wondrous works, or to remain silent.  The Lord knows best and instructed His disciples accordingly.  (CC)  (534.4)