"They swear by Allah to you to please you" with lies, "while Allah and His Messenger are more deserving that they should please Him" with sincerity from their hearts.
﴿يحلفُونَ بِاللَّه لكم ليرضوكم﴾ بِالْكَذِبِ ﴿وَاللَّهُ وَرَسُولُهُ أَحَقُّ أَنْ يرضوه﴾ بِالصّدقِ من قُلُوبهم