Jamieson, Fausset and Brown on 1 Timothy 4:16

16. Take heed--Give heed (Ac 3:5).

thyself, and ... doctrine--"and unto thy teaching." The two requisites of a good pastor: His teaching will be of no avail unless his own life accord with it; and his own purity of life is not enough unless he be diligent in teaching [Calvin]. This verse is a summary of 1Ti 4:12.

continue in them--(2Ti 3:14).

in doing this--not "by doing this," as though he could save himself by works.

thou shalt ... save thyself, and them that hear thee--(Eze 33:9; Jas 5:20). In performing faithfully his duty to others, the minister is promoting his own salvation. Indeed he cannot "give heed unto the teaching" of others, unless he be at the same time "giving heed unto himself."