Hadrat Shaykh Masihullah (may Allah have mercy on him) said,
“Nisba literally means relationship or connection.
A relationship or a connection is a two-way process. In our context the relationship with Allah means Allah’s connection with the servant and the servant’s connection with Allah Most High.
The attainment of relationship with Allah (nisba) is also referred to as wusul ila’Llah.
The relationship of Allah with the servant is Allah’s pleasure with His servant. The relationship of the servant with Allah means the servant’s constant obedience and involvement in abundant remembrance with perfect awareness.”
The Path to Perfection, page 112