Question Summary:
What is the Shar’ee ruling regarding taking a 2nd wife?

Question Detail:

Please advice on Shariah ruling if a man has to take on asecond wife.
Is it obligatory to obtain 1st wife’s consent?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykumwa-rahmatullāhiwa-barakaatuh.
 
According to Shariah, the husband is not obliged to obtain consent from his wife if he intends to remarry. However it will be most ethical and in the interest of  loyalty  in the marriage to inform the wife, of his intention to take another wife.
 
And Allah Ta’āla Knows Best
Saeed Ncane 
Student DarulIftaa
South Africa 
Checked and Approved by,
Mufti Ebrahim Desai.