مَنْ أُعْطِيَ عَطَاءً فَوَجَدَ فَلْيَجْزِ بِهِ وَمَنْ لَمْ
يَجِدْ فَلْيُثْنِ فَإِنَّ مَنْ أَثْنَى فَقَدْ شَكَرَ وَمَنْ كَتَمَ فَقَدْ كَفَرَ
وَمَنْ تَحَلَّى بِمَا لَمْ يُعْطَهُ كَانَ كَلَابِسِ ثَوْبَيْ زُورٍ
(قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ وَفِي
الْبَاب عَنْ أَسْمَاءَ بِنْتِ أَبِي بَكْرٍ وَعَائِشَةَ وَمَعْنَى قَوْلِهِ وَمَنْ
كَتَمَ فَقَدْ كَفَرَ يَقُولُ قَدْ كَفَرَ تِلْكَ النِّعْمَةَ)
"Whoever has a favor done to them should repay it. If he does not have that with which he can repay it, let him speak highly of him (i.e., the giver). For, if he speaks highly of him he has thanked him (shakarahu) but if he hides (or ignores) it, he has shown ingratitude (kafarahu). And, whoever makes a show of that which they have not been given, it is if they have dressed themselves in two garments of falsehood."
"Speak highly of him" (athnaa 'alaihi) here literally means "praise him" which include refraining from backbiting him and saying only positive things about him around others. In another hadith, the Prophet (sas) informs us that to say "jazaaka Allahu khairan" fulfills this completely:
مَنْ صُنِعَ إِلَيْهِ مَعْرُوفٌ فَقَالَ لِفَاعِلِهِ جَزَاكَ اللَّهُ خَيْرًا فَقَدْ أَبْلَغَ فِي الثَّنَاءِ
Kufr is the opposite of shukr - with Allah, with husbands and with people generally. Here, kufr means the failure to acknowledge favors and grants, acting as if it never happened or worse - having no gratitude for it at all. This is the case of someone who "expects" what they were given or impugns negative motivations to one who has done good to them.
"Makes a show of that which they have not been given" here means:
Claiming you were given something which you weren't - such as between co-wives as narrated in several hadith.
One who makes a show to make people think that he has more than he does in terms of wealth (An-Nawawi)
Wearing the garments and fashions of the people of piety, worship and remembrance though one is not doing any of those things (Abu Ubaid)
"Garments" here is an allegory for his way, manner or reality of his character. In other words, such a person is like some who told lies explicitly (Al-Khattabi).
Another possibility: one who was given by another but attempted to negate/conceal his role as if he had gotten what he has on his own the Author).
مَنْ اسْتَعَاذَ بِاللَّهِ فَأَعِيذُوهُ وَمَنْ سَأَلَ بِاللَّهِ فَأَعْطُوهُ وَمَنْ دَعَاكُمْ فَأَجِيبُوهُ وَمَنْ صَنَعَ إِلَيْكُمْ مَعْرُوفًا فَكَافِئُوهُ فَإِنْ لَمْ تَجِدُوا مَا تُكَافِئُونَهُ فَادْعُوا لَهُ حَتَّى تَرَوْا أَنَّكُمْ قَدْ كَافَأْتُمُوهُ (أبو داود)
"Whoever seeks refuge in Allah, give him refuge. Whoever asks you by Allah, give him. Whoever invites you, respond by attending. Whoever grants you favor, repay it. If you don't possess that with which you can repay it, then make du'a for him until you believe that you have repayed him."
Meaning whoever sought refuge in Allah and asked of you the prevention of evil/harm from yourself or from others. You should respond to his request if you are able. This does NOT include the sheltering of wrongdoers, as the Prophet (sas) said:
سَأَلَ رَجُلٌ عَلِيًّا هَلْ كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُسِرُّ إِلَيْكَ بِشَيْءٍ دُونَ النَّاسِ فَغَضِبَ عَلِيٌّ حَتَّى احْمَرَّ وَجْهُهُ وَقَالَ مَا كَانَ يُسِرُّ إِلَيَّ شَيْئًا دُونَ النَّاسِ غَيْرَ أَنَّهُ حَدَّثَنِي بِأَرْبَعِ كَلِمَاتٍ وَأَنَا وَهُوَ فِي الْبَيْتِ فَقَالَ لَعَنَ اللَّهُ مَنْ لَعَنَ وَالِدَهُ وَلَعَنَ اللَّهُ مَنْ ذَبَحَ لِغَيْرِ اللَّهِ وَلَعَنَ اللَّهُ مَنْ آوَى مُحْدِثًا وَلَعَنَ اللَّهُ مَنْ غَيَّرَ مَنَارَ الْأَرْضِ (النسائي)
When a new bride of the Prophet (sas) said, "I seek refuge in Allah from you", he (sas) replied, "You have sought the refuge of a Great One. Return to your family."
Do not ask for anything of this world by Allah. The hadith indicates this implicitly since it obligates the one asked by Allah to give and so asking in this manner places them in a difficult position and exposes them to a sin if they cannot or will not give to the asker. Ataa' strongly dislike asking for anything by Allah. However, it is also possible that this applies only to one who can give easily without impact on himself or his dependents and so the wajib exists and is not a hardship and otherwise, no.
لَا يَشْكُرُ اللَّهَ مَنْ لَا يَشْكُرُ النَّاسَ (أبو داود)
"He does not thank Allah who does not thank people."
Whoever does not have in his nature gratitude and expressing thanks to people will also not be among those who give thanks to Allah Most High and will not be granted success (taufeeq) to do that. Whoever is incapable of something minor will prove incapable of something more major without doubt. Allah said, {And if you count the favors of Allah you will never enumerate them all}. So the one who proves incapable of gratitude for the tiny favors of other Muslims will certainly never have true gratitude for that which is much larger.