It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) regarding the noble verse: «﴿فَأْتُوا حَرْثَكُمْ أَنَّى شِئْتُمْ﴾» that what is meant is that you may come from the front or the back (have intercourse), as long as penetration is only in the specified place.