The most distinct and measurable promise is in Mark.chapter 13, where Jesus promised that the world would end during the lifetimes of those then still living, prophesying they would see him return on clouds of glory. Jesus told his listeners that they would see the great buildings destroyed, and the abomination of desolation, followed by the Son of man coming in clouds of glory, and that this would take place during their own generation*. Mark 9:1 foreshadows the fuller account in chapter 13, saying that some of those who stand here will not taste death until they have seen the kingdom of God come with power.
Other promises are more vague and relate to an unknown afterlife. It is the unfulfilled promise in Mark chapter 13 that ought to establish our confidence in whether the promises for the afterlife can really be met.
*Mark 13:24-26: "But in those days, after that tribulation, the sun shall be darkened, and the moon shall not give her light and the stars of heaven shall fall, and the powers that are in heaven shall be shaken and then shall they see the Son of man coming in the clouds with great power and glory." Then: "Verily I say unto you, that this generation shall not pass, till all these things be done."
By the 80s of the first century, when Matthew's Gospel was written, the return predicted in Mark's Gospel was becoming unlikely - the generation had already passed - and the author of Matthew had to change the emphasis away from an impending end of the world. While copying as faithfully as possible from Mark, he changed the position of the sentence about "this generation", relative to the destruction of the great buildings, so that it referred to something else altogether. He added, and emphasised, material where Jesus told the disciples that the end is not yet, and that no man knows when the end of the world will occur.
u promise to follow they way Jesus acts.
as long as they had faith
Yes; He made a promise to jesus that he could not keep
Jesus has promised that he will return again soon to judge the world.
Eternal life with Him in heaven :D
Jesus promised to send his comfortor the holy spirit to his diciples. As always this promise came true and we read about it in Acts chapter 2.
that he will descend down to earth again for the judgement day.
This day you shall see me in paradise