What about using sticky prostatic fluid to insert the penis during intercourse?

If the emission of prostatic fluid (madhy) is natural during foreplay with the wife, then this might be part of the wisdom behind the matter. It is commendable for a man to engage in foreplay with his wife before intercourse to bring her comfort, tenderness, and to arouse her desire. However, if the hand is used to apply the madhy, this should not be done, as it involves handling impurity unnecessarily.