90. Why is the word jihad applied to the battles of the early Muslims?

Because these battles had to be fought for the very existence of the religion of Islam, and because the Muslims had to strive hard by risking their lives and by sacrificing their possessions. Taking part in these battles was a great struggle, done only to save Islam from destruction and no other reason. 

Before their emigration (hijra) to Madina, while living in Makka, the converts to Islam had to face terrible persecution and torture. But they bore it all with patience. In the Quran this was also called a jihad on their part. After the Muslims had been forced to emigrate to Madina, the opponents of Islam in Makka decided to wage war upon them. So the Muslims then had to fight battles in self-defence. As they had no proper army or equipment, each member of the Muslim community had to do, and to give, all that he or she could. They volunteered to fight in the battles, and gave their money and possessions for the war. Therefore this was called a jihad by means of one's life and property.

Non-Muslim

"Allah does not forbid you concerning those people who do not fight you because of your religion, nor expel you from your homes, that you show them kindness and deal with them justly.. . . Allah forbids you only concerning those people who fight you for your religion, and drive you from your homes and help others to expel you, that you make friends of them." (60: 8,9)

"Whatever good they (people of other religions) do, they will not be denied it (by Allah), and Allah knows who the righteous are." (3:115)

"O you who believe, be upright for Allah, bearers of witness with justice; and do not let the hatred of a people incite you not to act with justice. Be just; that is nearer to observance of duty." (5:8)

"Call (others) to the way of your Lord with wisdom and goodly exhortation, and argue with them in the best manner." (16:125) 

"Argue not with the people of the Book (Jews, Christians, and other people having scriptures) except by the best (means), save those of them who act unjustly. But say: We believe in that which has been revealed to us and revealed to you, and our God and your God is One, and to Him we submit." (29:46)

A companion of the Holy Prophet relates: 

"A funeral procession passed by the Holy Prophet, and he stood up for it. People said to him: It was the funeral of a Jew. He said: Was it not a human life?" (Report in Bukhari.) 

Husband and Wife

"They (your wives) are a garment for you, and you are a garment for them." (2:187)

"Of His (Allah's) signs is that He created spouses for you from yourselves so that you might find quiet of mind in them, and He put between you love and compassion." (30:21)

"The best of you are those who are kindest to their wives." (Holy Prophet in Tirmizi.) 

A man related:

"I asked Aishah (Holy Prophet's wife): What did the Prophet do when in his house? She said, `He served his wife', meaning that he did work for his wife." (Report in Bukhari.)