All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work. _ 2 Timothy 3:16,17

Let us never allow anybody to divide between the word of the apostles and the word of Christ. Our Savior has joined them together. “Neither pray I for these alone, but for them also which shall believe on Me through their word.” And if any begin rejecting the apostolic word, they will be outside the number for whom Christ prays; they shut themselves out by that very fact. I wish that they would solemnly recollect that the word of the apostles is the word of Christ. He tarried not long enough, after He had risen from the dead, to give us a further exposition of His mind and will; and He could not have given it before His death, because it would have been unsuitable. “I have yet many things to say unto you, but ye cannot bear them now.” After the descent of the Holy Ghost, the disciples were prepared to receive that which Christ spoke by His servants Paul and Peter, and James and John. Certain doctrines which we are sometimes taunted about as being not revealed by Christ, but by His apostles, were all revealed by Christ, every one of them. They can all be found in His teaching; but they are very much in the parabolic form. It is after He has gone up into glory and has prepared a people by His Spirit to understand the truth more fully, that He sends His apostles, and says, “Go forth, and open up to those whom I have chosen out of the world the meaning of all I said.” The meaning is all there, just as all the New Testament is in the Old; and sometimes I have thought that, instead of the Old being less inspired than the New, it is more inspired. Things are packed away more tightly in the Old Testament than in the New, if possible. There are worlds of meaning in one pregnant line in the Old Testament; and in Christ’s words it is just so. He is the Old Testament to which the Epistles come in as a kind of New Testament; but they are all one and indivisible; they cannot be separated. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/2213.cfm