Hadith 8:181
Narrated 'Umar (RA) regarding a wife of a lost husband:
She should wait for four years and then observe the 'Iddah for four months and ten days (before she may remarry). [Malik and ash-Shafi'i reported it].
وَعَنْ عُمَرَ - رضى الله عنه - - { فِي اِمْرَأَةِ اَلْمَفْقُودِ- تَرَبَّصُ أَرْبَعَ سِنِينَ, ثُمَّ تَعْتَدُّ أَرْبَعَةَ أَشْهُرٍ وَعَشْرًا } . أَخْرَجَهُ مَالِكٌ, وَالشَّافِعِيُّ