مَن ذَا الَّذِي يُقْرِضُ اللَّهَ قَرْضًا حَسَنًا
Who is he that will lend Allah a handsome loan?
Umar bin Al-Khattab said that this Ayah refers to spending in Allah's cause.
It was also said that it pertains to spending on children.
What is correct is that it is more general than that. So all those who spend in the cause of Allah with good intentions and a sincere heart, then they fall under the generality of this Ayah. This is why Allah the Exalted said;
مَّن ذَا الَّذِي يُقْرِضُ اللّهَ قَرْضًا حَسَنًا فَيُضَاعِفَهُ لَهُ
Who is he that will lend Allah handsome loan;then (Allah) will increase it manifold to his credit (in repaying), and in another Ayah,
أَضْعَافًا كَثِيرَةً
(many times) (2;245),
meaning, being handsome reward and tremendous provisions;Paradise on the Day of Resurrection.
Ibn Abi Hatim recorded that Abdullah bin Masud said,
"When this Ayah,
مَّن ذَا الَّذِي يُقْرِضُ اللّهَ قَرْضًا حَسَنًا فَيُضَاعِفَهُ لَهُ
(Who is he that will lend Allah handsome loan;then (Allah) will increase it manifold to his credit (in repaying),) was revealed, Abu Ad-Dahdah Al-Ansari said, `O Allah's Messenger! Does Allah ask us for a loan' The Prophet said,
Yes, O Abu Ad-Dahdah.
He said, `Give me your hand, O Allah's Messenger,'
and the Prophet placed his hand in his hand.
Abu Ad-Dahdah said, `Verily, I have given my garden as a loan to my Lord.'
He had a garden that contained six hundred date trees; his wife and children were living in that garden too.
Abu Ad-Dahdah went to his wife and called her, Umm Ad-Dahdah!'
She said, `Here I am.'
He said, `Leave the garden, because I have given it as a loan to my Lord, the Exalted and Most Honored.'
She said, `That is a successful trade, O Abu Ad-Dahdah!'
She then transferred her goods and children.
The Messenger of Allah said,
كَمْ مِنْ عَذْقٍ رَدَاحٍ فِي الْجَنَّةِ لاَِبِي الدَّحْدَاح
How plentiful are the sweet date clusters that Abu Ad-Dahdah has in Paradise!"
In another narration, the Prophet said,
رُبَّ نَخْلَةٍ مُدَلاَّةٍ عُرُوقُهَا دُرٌّ وَيَاقُوتٌ لاَِبِي الدَّحْدَاحِ فِي الْجَنَّة
How many a date tree that has lowered down its clusters, which are full of pearls and gems in Paradise for Abu Ad-Dahdah!
وَلَهُ أَجْرٌ كَرِيمٌ
and he will have a honorable reward.