All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger.
Laws that are established for a clear public interest or to prevent an evident public harm are not permissible to be violated, and what is done to circumvent them is considered a forbidden bribe. 'Abdullah ibn 'Amru reported that the Messenger of Allah, sallallaahu 'alayhi wa sallam, 'cursed both the one who gives a bribe (the briber) and the one who takes it (the bribed)'. This is reported by At-Tirmidhi, and he classified it as Hasan (Good) and Authentic.
The fact that a person wants profit and the prosperity of his business does not justify him violating what is forbidden for the sake of the public interest.
However, this does not make the earnings your husband made from selling apartments forbidden. Rather, there is no blame on him for benefiting from it, but he is sinning by his violation and bribing, according to what we explained before.
Allah knows best.