First of all, the BIGGEST mistake most muslims do these days, in guiding others is that they do not know that its ALLAH who guides people, its ALLAH who controls the hearts, we dont. Our job , according to Quran is only Tell them what is right , and that too in a very generous and soft manner.
Here are some of the verses about it:
[64:11] No disaster strikes except by permission of Allah. And whoever
believes in Allah - He will guide his heart. And Allah is Knowing of
“…Thus does Allah leave astray whom He wills and guides whom He wills.
Indeed, [O Muhammad], you do not guide whom you like, but Allah guides
whom He wills. And He is most knowing of the [rightly] guided. (Qur’an
So, dont assume that YOU will guide his heart, but just believe that your job is just to convey the message in most beautiful manner, As Allah says in Quran:
12.108 "Say: "This is my Way: I do invite unto Allah,- with certain knowledge, - I and whoever follows me. Glory to Allah, and never will I join gods with Allah!"
16.125 "Invite (all) to the Way of thy Lord with wisdom and beautiful preaching; and argue with them in ways that are best and most
gracious: for thy Lord knows best, who have strayed from His Path, and
who receive guidance."
22.67 "To every People have We appointed rites which they must follow: let them not then dispute with thee on the matter, but do invite
(them) to thy Lord: for thou art assuredly on the Right Way."
28.87 "Let no one turn you away from Allah's revelations after they have been revealed to thee: and invite (men) to thy Lord, and be not
of the company of those who join gods with Allah."
So, the point now is what you have to do.
First, you must not make him stubborn or remind him about prayer again and again. Most muslims do this mistake these days that they ask others to do those islamic acts, about which they are not even aware that WHY they have to do it. As he leaves prayer like this, then it means that he surely does not know that who is Allah, and what is value and benefits of prayer, and WHY exactly he has to pray. So your first job is NOT just to say him "you have to pray, you have to pray", but talk to him about value of Prayer. Casua;lly ask him questions like "Why do muslims pray", "What is reason beind praying", Arrange an Islamic quiz with him, and say "lets see who wins in it"
you just have to make sure that you do dawah to him, in a manner, in which he is most comfortable, because if you got harsh, said the same thing again and again, then instead of praying, he will RUN AWAY from prayer..
Prophet Muhammad said:
“Make things easy for people and not difficult. Give people good news
and bring them joy, and do not turn them away."
In the end , JUST keep praying to Allah in your own way, that May Allah guide him to right path.
Other than this, here are some tips, to do dawah to people: