Imlaaq means poverty. It was the custom of the people of the Jaahiliyyah to bury their daughters alive, either because of poverty, or for fear that they may fall into poverty in the future. Allaah forbade it in either case. The first verse (interpretation of the meaning): 

“kill not your children because of poverty”

[al-An’aam 6:151]

refers to the first reason, i.e., do not kill your children because you are poor, because Allaah has guaranteed to provide for you and for them. 

And the second verse (interpretation of the meaning): 

“And kill not your children for fear of poverty. We shall provide for them as well as for you”

[al-Isra’ 17:31]

refers to the second reason, i.e., do not kill your children for fear that you may become poor or that they may become poor after you are gone, for Allaah will provide for them and for you. 

Ibn Katheer (may Allaah have mercy on him) said: With regard to the phrase “because of poverty [min imlaaqin]”, Ibn ‘Abbaas said: this means poverty, i.e., do not kill them because you are poor. It says in Soorat al-Isra’: “And kill not your children for fear of poverty”, i.e., do not kill them for fear of poverty in the future. Hence Allaah says here, “We shall provide for them as well as for you”. Here Allaah mentions their provision first, because of the concern for them, i.e., do not fear becoming poor because of providing for them, for that is what Allaah will do. But in the first verse, because poverty is already a factor, Allaah says, “We provide sustenance for you and for them”, because that is more important in that case. 

And Allaah knows best. 

End quote. 

And Allaah knows best.