Every night Allah (swt) descends to the lowest heavens. He (swt) calls out saying “Who is there seeking forgiveness so I can forgive them?” “Who is there asking for any of their needs so I can give?”. 

It is an open invitation from Allah, Here He is, ready to give and forgive us.

Even if you have not prayed tahajjud, wake up and make dua. Allah is calling us!