Study to show yourselves approved! ( 2 Tim 2:15 )

2 Timothy 2:15
"Be diligent to present yourself approved to God, a worker who does not need to be ashamed, rightly dividing the word of truth."

Apostle Paul instructed his disciple Timothy to be diligent in presenting himself approved by God, how? by rightly dividing the word
of Truth."
What or who is the source of Truth?
(John 14:6)
Jesus saith unto him, "I am the way, and the truth, and the life: no one comes unto the Father, but by me. "