Adam Clarke on Matthew 19:21

If thou wilt be perfect - Τελειος ειναι, To be complete, to have the business finished, and all hinderances to thy salvation removed, go and sell that thou hast - go and dispose of thy possessions, to which it is evident his heart was too much attached, and give to the poor - for thy goods will be a continual snare to thee if thou keep them; and thou shalt have treasure in heaven - the loss, if it can be called such, shall be made amply up to thee in that eternal life about which thou inquirest; and come and follow me - be my disciple, and I will appoint thee to preach the kingdom of God to others. This was the usual call which Christ gave to his disciples. See Mat 4:19; Mat 8:22; Mat 9:9; Mar 2:14; and it is pretty evident, from this, that he intended to make him a preacher of his salvation. How many, by their attachment to filthy lucre, have lost the honor of becoming or continuing ambassadors for the Most High! See on Mar 10:21 (note).