Albert Barnes on John 11:15

I am glad, &c. The meaning of this verse may be thus expressed: "If I had been there during his sickness, the entreaties of his sisters and friends would have prevailed with me to restore him to health. I could not have refused them without appearing to be unkind. Though a restoration to health would have been a miracle, and sufficient to convince you, yet the miracle of raising him after four days dead will be far more impressive, and on that account I rejoice that an opportunity is thus given so strikingly to confirm your faith."

To the intent. To furnish you evidence on which you might be established in the belief that I am the Messiah.