Marrying the wife's sister after the former's death
Is it permissible to marry my sister-in-law 48 days after my wife's death?
It is permissible to marry your sister-in-law since the prohibition only concerns marrying two sisters simultaneously. Allah the Almighty said about prohibitions in marriage:
"And [also prohibited are] … that you take [in marriage] two sisters simultaneously …" [Qur`an 4:23]
Therefore, if a wife passes away, it is permissible for her widower to marry her sister without waiting for any time to elapse.
According to the opinion of the majority of scholars, in the event the wife is irrevocably divorced, her divorcee may marry her sister without waiting for his ex-wife's 'idda [waiting period after divorce] to end. Hanafi scholars, on the other hand, maintained that a man is to wait for the 'idda to end before marrying her sister.
Allah Almighty knows best