If a man's marriage fulfils "half his deen", what happens with multiple wives?

Question

The question Are the "half your deen" hadiths authentic? talks about the hadiths regarding a man's marriage being half his deen. For example, Daily Hadith write:

Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said, “Whoever Allah provides with a righteous wife, then Allah has assisted him in half of his religion. Let him fear Allah regarding the second half.”

Source: al-Mu’jam al-Awsaṭ 992

Grade: Sahih (authentic) according to As-Suyuti

In Islam, a man is permitted to have N ∈ {0,1,2,3,4} wives. We know:

• If a man has 0 wives, 0% of his deen is fulfilled by virtue of having a wife.
• If a man has 1 wife, 50% of his deen is fulfilled by virtue of having a wife.

But what about N ∈ {2,3,4}?

Question: If a man's marriage fulfils "half his deen", what happens with multiple wives?

If we assume the level of fulfilment scales linearly with N, then a man fulfils N/2 of his deen by virtue of being married, which gives a contradiction when N ∈ {3,4} because N/2>1. Therefore, the level of fulfilment cannot scale linearly with N. In other words, e.g. having three wives cannot be three times as virtuous as having one wife.

Answer 1

The hadith you quoted has another version in Al-Tabarani's Al-Mu'jam Al-Awṣat, hadith 7647, starting with "Whoever gets married, ..." (also narrated through Anas ibn Mālik). The condition set forth is being married. When the condition of marriage is fulfilled, one may have fulfilled half of one's religion. Multiple marriages, concurrent or in sequence, are still treated in a binary fashion, rather than elements of a set, or on a linear scale.

The reason being married is fulfillment of half of the religion is that the Prophet ﷺ said that two evils when one is spared, one will enter Jannah:

عن أبي هريرة رضي الله عنه‏ أن رسول الله ﷺ قال:‏ ‏ومن وقاه الله شر ما بين لحييه وشر ما بين رجليه دخل الجنة

Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) said, "He whom Allah saves from the evil of that which is between his jaws and the evil of that which is between his legs will enter Jannah."

_{— Riyad as-Sāliḥīn » Book 18 » Hadith 9}

Marriage assists one in guarding what is between one's legs; hence, the one-half connotation. More than one wife constitutes one-half regardless, as it is related to the status, not the count.