2 Timothy 1:4

Greatly desiring to see thee
In his former epistle he had desired him to stay at Ephesus, there being some work for him to do, which made it necessary he should continue; but now having answered the apostle's purpose, and he standing in need of him at Rome, being without any assistant there, some having left him, and others were left by him in other places, and others were sent by him elsewhere; and it having been some time since he saw Timothy, he longed for a sight of him:

being mindful of thy tears;
shed either at the afflictions and sufferings of the apostle, of which Timothy, being his companion, was an eyewitness, and he being of a truly Christian sympathizing spirit, wept with those that wept; or at their parting from each other, as in ( Acts 20:37 Acts 20:38 )

that I may be filled with joy;
at the sight of him, and not at the remembrance of his tears; for the last clause is to be read in a parenthesis, and these words stand not connected with that, but with the preceding part of the text. The apostle intimates, that a sight of his dearly beloved son Timothy would fill him with joy amidst all his troubles and afflictions he endured for the Gospel: this is an instance of hearty, sincere, and strong affection.