Hazrat N’umaan bin Bashir (RA) said, “Nabi Sallallahu Alayhi Wasallam used to straighten our rows, as if he was straightening a (bent) arrow by means of our saffs , until he saw that we had learnt it, ie straightening of saffs. Then he came out one day and was about to say the Takbir (to commence the Salaat), when he noticed a man whose chest was protruding out of the row. He said: Oh Slaves of Allah! Make your rows straight, or else Allah will cause discord amongst you.” ~ [Sahih Muslim]
Important aspects discussed in this Hadith :
• The Importance of straightening the rows for congregational Salaat.
• Allah creates discord/disunity/disharmony amongst the people who do not keep their rows straight.