Atharva Veda 6.72

For virile power

As the black snake spreads himself at pleasure, making wondrous forms (vápus), by the Asura's magic (māyá), so let this arid suddenly make thy member altogether correspondent (? sáṁsamaka), limb with limb.

As the member of the tayādara is made big by the wind—as great as is the member of the párasvant, so great let thy member grow.

As much of a limb as is that of the párasvant, that of the elephant, and that of the ass—as great as of the vigorous (vājín) horse, so great let thy member grow.