John 14:3 - Matthew Poole's English Annotations on the Holy Bible

The particle if in this place denotes no uncertainty of the thing whereof he had before assured them; but in this place hath either the force of although, or after that: When, or after that, I have died, ascended, and by all these acts, as also by my intercession, shall have made places in Heaven fully ready for you, I will in the last day return again, as Judge of the quick and the dead, and take you up into heaven, 1 Thessalonians 4:16,17; that you may be made partakers of my glory, 1 Thessalonians 17:22. This is called, Romans 8:17, a being glorified together with him; and elsewhere, a reigning with him. So as this is a third argument by which our Lord comforteth his disciples as to their trouble conceived for the want of His bodily presence with them, from the certainty of his return to them, and the end and consequent of his return: the end was to receive them to himself; the consequent, their eternal abiding with Christ where he was.